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<title>Document</title></head><body><div id="i78777d12badf401387c0eea2cb2dd41d_1"></div><div style="min-height:49.5pt;width:100%"><div style="text-align:center"><font><br></font></div></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">As filed with the Securities and Exchange Commission on May 11, 2021</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:right"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Registration No.&#160;333-   </font></div><div><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:4pt;font-weight:400;line-height:120%">&#160;</font></div><div style="margin-bottom:1pt;text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:99.882%"><tr><td style="width:1.0%"></td><td style="width:98.900%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:400;line-height:120%">&#160;&#160;</font></td></tr></table></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:18pt;font-weight:700;line-height:120%">UNITED STATES </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:18pt;font-weight:700;line-height:120%">SECURITIES AND EXCHANGE COMMISSION </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:700;line-height:120%">Washington, D.C. 20549 </font></div><div style="margin-bottom:1pt;text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:18pt;font-weight:700;line-height:120%">FORM S-8 </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:700;line-height:120%">REGISTRATION STATEMENT UNDER </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:700;line-height:120%">THE SECURITIES ACT OF 1933 </font><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:400;line-height:120%">&#160;</font></div><div style="margin-top:7pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:18pt;font-weight:700;line-height:120%">EXAGEN INC. </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">(Exact name of registrant as specified in its charter) </font><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:400;line-height:120%">&#160;</font></div><div style="margin-bottom:1pt;text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:89.630%"><tr><td style="width:1.0%"></td><td style="width:32.886%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.780%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:30.926%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.780%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:30.928%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:400;line-height:120%">&#160;</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Delaware</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#160;</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#160;</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">20-0434866</font></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">(State or other jurisdiction of</font></div><div style="margin-bottom:1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">incorporation or organization)</font></div></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">&#160;</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">&#160;</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">(I.R.S. Employer</font></div><div style="margin-bottom:1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">Identification No.)</font></div></td></tr></table></div><div style="margin-top:7pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">1261 Liberty Way </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Vista, California 92081 </font></div><div style="margin-top:4pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">(Address of principal executive offices) (Zip code) </font></div><div style="margin-top:7pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Exagen Inc. 2019 Incentive Award Plan</font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Exagen Inc. 2019 Employee Stock Purchase Plan</font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">(Full title of the plans)</font></div><div style="text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:99.882%"><tr><td style="width:1.0%"></td><td style="width:98.900%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="border-bottom:1pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:400;line-height:120%">&#160;</font></td></tr></table></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Fortunato Ron Rocca </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">President and Chief Executive Officer </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Exagen Inc. </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">1261 Liberty Way </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Vista, California 92081 </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">(760) 560-1501 </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">(Name, address, and telephone number, including area code, of agent for service) &#160;</font></div><div style="margin-bottom:1pt;margin-top:8pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of &#8220;large accelerated filer,&#8221; &#8220;accelerated filer,&#8221; &#8220;smaller reporting company,&#8221; and &#8220;emerging growth company&#8221; in Rule 12b-2 of the Exchange Act. </font></div><div><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:400;line-height:120%">&#160;</font></div><div style="margin-bottom:1pt;margin-top:6pt;text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:92.120%"><tr><td style="width:1.0%"></td><td style="width:20.521%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:20.521%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:7.962%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:24.973%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:20.523%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Large accelerated filer</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#9744;</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Accelerated filer</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#9744;</font></td></tr><tr style="height:5pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Non-accelerated filer</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#9746;</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Smaller reporting company</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#9746;</font></td></tr><tr style="height:5pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Emerging growth company</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#9746;</font></td></tr></table></div><div style="margin-top:8pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act </font><font style="font-family:'Wingdings',sans-serif;font-size:10pt;font-weight:400;line-height:120%"></font></div><div><font><br></font></div><div style="margin-top:2pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">CALCULATION OF REGISTRATION FEE</font></div><div style="height:43pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div><hr style="page-break-after:always"><div style="min-height:49.5pt;width:100%"><div style="text-align:center"><font><br></font></div></div><div style="margin-bottom:6pt;text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:99.882%"><tr><td style="width:1.0%"></td><td style="width:32.770%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:13.122%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:15.762%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:15.908%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:16.938%"></td><td style="width:0.1%"></td></tr><tr style="height:6pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="border-top:3pt double #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Title of Securities to be Registered</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:3pt double #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Amount to be Registered (1)</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:3pt double #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Proposed Maximum Offering Price per Share (2)</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:3pt double #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Proposed Maximum Aggregate Offering Price (2)</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:3pt double #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Amount of Registration Fee</font></td></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Common stock, $0.001 par value</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">1,008,532 (3)</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">$15.30</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">$15,430,539.60</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">$1,683.47</font></td></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Common stock, $0.001 par value</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">252,133 (4)</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">$15.30</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">$3,857,634.90</font></td><td colspan="3" style="border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">$420.87</font></td></tr><tr><td colspan="3" style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Total</font></td><td colspan="3" style="border-bottom:3pt double #000;border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">1,260,665</font></td><td colspan="3" style="border-bottom:3pt double #000;border-left:1pt solid #000;border-top:1pt solid #000;padding:0 1pt"></td><td colspan="3" style="border-bottom:3pt double #000;border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">$19,288,174.50</font></td><td colspan="3" style="border-bottom:3pt double #000;border-left:1pt solid #000;border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">$2,104.34</font></td></tr></table></div><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:99.882%"><tr><td style="width:1.0%"></td><td style="width:2.272%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.973%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:94.355%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(1)</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">Pursuant to Rule 416(a) of the Securities Act of 1933, as amended (the &#34;Securities Act&#34;), this Registration Statement also registers an indeterminate number of additional shares that may be issued pursuant to the above-named plans as a result of any future stock dividend, stock split, recapitalization or any other similar transaction effected without receipt of consideration which results in an increase in the number of our outstanding shares of common stock.</font></td></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(2)</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">Estimated in accordance with Rule 457(c) of the Securities Act solely for the purpose of calculating the registration fee. The Proposed Maximum Offering Price per Share and the Proposed Maximum Aggregate Offering Price are based upon the average of the high and low prices of the Registrant's common stock as reported on the Nasdaq Global Market on May 6, 2021, which date is within five business days prior to filing this Registration Statement.</font></td></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(3)</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">Represents additional shares of the Registrant's common stock that became available for issuance under the 2019 Plan, pursuant to the evergreen provision of the 2019 Plan.</font></td></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(4)</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">Represents additional shares of the Registrant's common stock that became available for issuance under the 2019 ESPP, pursuant to the evergreen provision of the 2019 ESPP.</font></td></tr></table></div><div style="margin-top:7pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Proposed sales to take place as soon after the effective date of the Registration Statement as awards granted under the above-named plans are granted, exercised and&#47;or distributed. </font></div><div style="text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:99.882%"><tr><td style="width:1.0%"></td><td style="width:98.900%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:12pt;font-weight:400;line-height:120%">&#160;</font></td></tr></table></div><div><font><br></font></div><div style="height:43pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div><div id="i78777d12badf401387c0eea2cb2dd41d_343"></div><hr style="page-break-after:always"><div style="min-height:72pt;width:100%"><div style="text-align:center"><font><br></font></div></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">EXPLANATORY NOTE</font></div><div style="margin-top:12pt;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">This Registration Statement on Form S-8 is being filed with the Securities and Exchange Commission for the purpose of registering an additional 1,260,665 shares of common stock of  Exagen Inc. (the &#34;Registrant&#34;) issuable or which may become issuable under the Exagen Inc. 2019 Incentive Award Plan (the &#34;2019 Plan&#34;) and the Exagen Inc. 2019 Employee Stock Purchase Plan (the &#34;2019 ESPP&#34;) pursuant to the evergreen provision of such plans.</font></div><div style="margin-top:12pt;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Pursuant to General Instruction E on Form S-8, the contents of the prior registration statement on Form S-8, File No. 333-233878, previously filed with respect to the 2019 Plan and 2019 ESPP, are incorporated into this Registration Statement by reference to the extent not modified or superseded hereby or by any subsequently filed document, which is incorporated by reference herein or therein. </font></div><div id="i78777d12badf401387c0eea2cb2dd41d_350"></div><div style="margin-top:12pt;text-align:center;text-indent:18pt"><font><br></font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">PART I</font></div><div style="margin-top:12pt;text-align:center;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS</font></div><div style="margin-top:12pt;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The documents containing the information specified in Part I of Form S-8 will be sent or given to participants as specified by Rule 428(b)(1) of the Securities Act. These documents and the documents incorporated by reference into this Registration Statement pursuant to Item 3 of Part II of this Registration Statement, taken together, constitute a prospectus that meets the requirements of Section 10(a) of the Securities Act.</font></div><div id="i78777d12badf401387c0eea2cb2dd41d_357"></div><div style="margin-top:12pt;text-align:center;text-indent:18pt"><font><br></font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">PART II</font></div><div style="margin-top:12pt;text-align:center;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">INFORMATION REQUIRED IN THE REGISTRATION STATEMENT</font></div><div style="margin-top:12pt;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">In this Registration Statement, Exagen Inc. is sometimes referred to as &#34;Registrant,&#34; &#34;we,&#34; &#34;us&#34; or &#34;our.&#34;</font></div><div style="margin-top:12pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Item 3. Incorporation of Documents by Reference</font></div><div style="margin-top:12pt;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The Securities and Exchange Commission (&#34;SEC&#34;) allows us to &#34;incorporate by reference&#34; the information we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this Registration Statement, and later information filed with the SEC will update and supersede this information. We hereby incorporate by reference into this Registration Statement the following documents previously filed with the SEC&#58;</font></div><div style="margin-top:6pt;padding-left:36pt;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#8226;</font><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">The Registrant's Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 16, 2021 and Amendment No. 1 to the Registrant's Annual Report on Form 10-K&#47;A for the year ended December 31, 2020, filed with the SEC on April 1, 2021&#59;</font></div><div style="margin-top:6pt;padding-left:36pt;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#8226;</font><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">The Registrant's Current Reports on Form 8-K filed with the SEC on March 22, 2021 and March 23, 2021&#59;</font></div><div style="margin-top:6pt;padding-left:36pt;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#8226;</font><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">The Registrant's Definitive Proxy Statement on Schedule 14A, filed with the SEC on April 27, 2021&#59; and</font></div><div style="margin-top:6pt;padding-left:36pt;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#8226;</font><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">The description of the Registrant's common stock set forth in the Registrant's registration statement on Form 8-A12B (Registration No. 001-39049), filed by the Registrant with the SEC under Section 12(b) of the Securities Exchange Act of 1934, as amended (the &#34;Exchange Act&#34;), on September 13, 2019, including any amendments or reports filed for the purpose of updating such description.</font></div><div style="margin-top:12pt;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In addition, all documents filed by the Registrant pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the filing of this registration statement and prior to the filing of a post-effective amendment which </font></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div><hr style="page-break-after:always"><div style="min-height:72pt;width:100%"><div style="text-align:center"><font><br></font></div></div><div style="margin-top:12pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">indicates that all securities offered hereby have been sold or which de-registers all securities then remaining unsold shall be deemed to be incorporated by reference into this registration statement and to be a part hereof from the date of filing such documents, except as to specific sections of such statements as set forth therein. Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this registration statement to the extent that a statement contained herein or in any other subsequently filed document which also is incorporated or deemed to be incorporated by reference herein modifies or supersedes such statement. Any statement contained herein shall be deemed to be modified or superseded for purposes of this registration statement to the extent that a statement contained in any subsequently filed document which also is incorporated or deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this registration statement.</font></div><div style="margin-top:12pt;text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Under no circumstances shall any information furnished under Item 2.02 or 7.01 of Form 8-K be deemed incorporated herein by reference unless such Form 8-K expressly provides to the contrary.</font></div><div style="margin-top:12pt;text-indent:18pt"><font><br></font></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div><div id="i78777d12badf401387c0eea2cb2dd41d_364"></div><hr style="page-break-after:always"><div style="min-height:72pt;width:100%"><div style="text-align:center"><font><br></font></div></div><div style="text-align:center"><font><br></font></div><div style="-sec-extract:summary;text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">EXHIBIT INDEX</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:7.393%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:32.393%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:8.675%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:12.521%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:8.034%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:10.278%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:13.006%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="12" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">Incorporated by Reference</font></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">Exhibit Number</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">Exhibit Description</font></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">Form</font></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">File No.</font></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">Exhibit</font></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">Exhibit Filing Date</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">Filed&#47;Furnished Herewith</font></td></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">3.1</font></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="http://www.sec.gov/Archives/edgar/data/1274737/000119312519252366/d769261dex31.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Form of Amended and Restated Certificate of Incorporation.</a></font></div></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">8-K</font></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">001-39049</font></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">3.1</font></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">9&#47;23&#47;2019</font></td><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">3.2</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="http://www.sec.gov/Archives/edgar/data/1274737/000127473721000017/ex31-amendedandrestatedbyl.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Form of Amended Restated Bylaws.</a></font></div></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">8-K</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">001-39049</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">3.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">3&#47;22&#47;2021</font></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">4.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="http://www.sec.gov/Archives/edgar/data/1274737/000119312519240403/d692844dex41.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Specimen stock certificate evidencing the shares of common stock.</a></font></div></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">S-1&#47;A</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">333-233446</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">4.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">9&#47;9&#47;2019</font></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">5.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="ex51opinion-formsx8registr.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Opinion of Latham &#38; Watkins LLP.</a></font></div></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">X</font></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="http://www.sec.gov/Archives/edgar/data/1274737/000119312519240403/d692844dex103.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Exagen Inc. 2019 Incentive Award Plan.</a></font></div></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">S-1&#47;A</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">333-233446</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10.3</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">9&#47;9&#47;2019</font></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10.2</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="http://www.sec.gov/Archives/edgar/data/1274737/000119312519240403/d692844dex104.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Form of Option Agreement under Exagen Inc. 2019 Incentive Award Plan</a><a href="http://www.sec.gov/Archives/edgar/data/1274737/000119312519240403/d692844dex104.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">.</a></font></div></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">S-1&#47;A</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">333-233446</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10.4</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">9&#47;9&#47;2019</font></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10.3</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="http://www.sec.gov/Archives/edgar/data/1274737/000127473721000015/ex105-formofrsuagreement20.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Form of Restricted Stock Unit Agreement under Exagen Inc. 2019 Incentive Award Plan.</a></font></div></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10-K</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">001-39049</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10.5</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">3&#47;16&#47;2021</font></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10.4</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="http://www.sec.gov/Archives/edgar/data/1274737/000119312519240403/d692844dex105.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Exagen Inc. 2019 Employee Stock Purchase Plan</a><a href="http://www.sec.gov/Archives/edgar/data/1274737/000119312519240403/d692844dex105.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">.</a></font></div></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">S-1&#47;A</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">333-233446</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">10.5</font></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">9&#47;9&#47;2019</font></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">23.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="ex231-bdosx8consent.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Consent of BDO USA, LLP, independent registered public accounting firm.</a></font></div></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">X</font></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">23.2</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="ex51opinion-formsx8registr.htm" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Consent of Latham &#38; Watkins LLP (included in Exhibit 5.1).</a></font></div></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">X</font></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">24.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><font style="color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="#i78777d12badf401387c0eea2cb2dd41d_372" style="-sec-extract:exhibit;color:#0000ff;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;text-decoration:underline">Power of Attorney (see signature page)</a></font></div></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">X</font></td></tr></table></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div><div id="i78777d12badf401387c0eea2cb2dd41d_372"></div><hr style="page-break-after:always"><div style="min-height:72pt;width:100%"><div style="text-align:center"><font><br></font></div></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">SIGNATURES</font></div><div style="text-align:center"><font><br></font></div><div style="text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Pursuant to the requirements of the Securities Act, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Vista, State of California, on May 11, 2021.</font></div><div><font><br></font></div><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:56.762%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:4.854%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:35.084%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">EXAGEN INC.</font></td></tr><tr style="height:15pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">by&#58;</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Fortunato Ron Rocca</font></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Fortunato Ron Rocca</font></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">President and Chief Executive Officer</font></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">(Principal Executive Officer)</font></td></tr></table></div><div><font><br></font></div><div style="text-indent:18pt"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Each person whose signature appears below hereby constitutes and appoints Fortunato Ron Rocca and Kamal Adawi, and each of them singly (with full power to each of them to act alone), his attorneys-in-fact, each with the full power of substitution, for him in any and all capacities, to sign this registration statement, and any amendments thereto (including post-effective amendments), and to file the same, with all exhibits thereto and other documents in connection therewith, with the SEC, hereby ratifying and confirming all that each of said attorneys-in-fact, or his substitute or substitutes, may do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act, this registration statement has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated.</font></div><div style="text-indent:18pt"><font><br></font></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div><hr style="page-break-after:always"><div style="min-height:72pt;width:100%"><div style="text-align:center"><font><br></font></div></div><div style="text-align:center;text-indent:18pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:4.829%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:20.534%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.441%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:48.739%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.601%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:20.056%"></td><td style="width:0.1%"></td></tr><tr><td colspan="6" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Signature</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Title</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Date</font></td></tr><tr style="height:5pt"><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"></td><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"></td></tr><tr><td colspan="6" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Fortunato Ron Rocca</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">President, Chief Executive Officer and Director</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Fortunato Ron Rocca</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">(Principal Executive Officer)</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr style="height:9pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="6" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Kamal Adawi</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Chief Financial Officer and Corporate Secretary</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Kamal Adawi</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">(Principal Financial and Accounting Officer)</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr style="height:9pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="6" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Brian Birk</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Chairman of the Board of Directors</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Brian Birk</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr style="height:9pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="6" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Jeff Elliott</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Director</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Jeff Elliott</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr style="height:9pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="6" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Wendy S. Johnson</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Director</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Wendy S. Johnson</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr style="height:9pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="6" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Tina S. Nova, Ph.D.</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Director</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Tina S. Nova, Ph.D.</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr style="height:9pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="6" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Ebetuel Pallares, Ph.D.</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Director</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Ebetuel Pallares, Ph.D.</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr style="height:9pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="6" style="border-bottom:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">&#47;s&#47; Bruce C. Robertson, Ph.D.</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Director</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Bruce C. 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Tullis</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Director</font></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">May 11, 2021</font></td></tr><tr><td colspan="6" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">James L.L. 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Document
As filed with the Securities and Exchange Commission on May 11, 2021
Registration No. 333-
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM S-8
REGISTRATION STATEMENT UNDER
THE SECURITIES ACT OF 1933
EXAGEN INC.
(Exact name of registrant as specified in its charter)
Delaware
20-0434866
(State or other jurisdiction of
incorporation or organization)
(I.R.S. Employer
Identification No.)
1261 Liberty Way
Vista, California 92081
(Address of principal executive offices) (Zip code)
Exagen Inc. 2019 Incentive Award Plan
Exagen Inc. 2019 Employee Stock Purchase Plan
(Full title of the plans)
Fortunato Ron Rocca
President and Chief Executive Officer
Exagen Inc.
1261 Liberty Way
Vista, California 92081
(760) 560-1501
(Name, address, and telephone number, including area code, of agent for service)
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.
Large accelerated filer
☐
Accelerated filer
☐
Non-accelerated filer
☒
Smaller reporting company
☒
Emerging growth company
☒
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act
CALCULATION OF REGISTRATION FEE
Title of Securities to be Registered
Amount to be Registered (1)
Proposed Maximum Offering Price per Share (2)
Proposed Maximum Aggregate Offering Price (2)
Amount of Registration Fee
Common stock, $0.001 par value
1,008,532 (3)
$15.30
$15,430,539.60
$1,683.47
Common stock, $0.001 par value
252,133 (4)
$15.30
$3,857,634.90
$420.87
Total
1,260,665
$19,288,174.50
$2,104.34
(1)
Pursuant to Rule 416(a) of the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement also registers an indeterminate number of additional shares that may be issued pursuant to the above-named plans as a result of any future stock dividend, stock split, recapitalization or any other similar transaction effected without receipt of consideration which results in an increase in the number of our outstanding shares of common stock.
(2)
Estimated in accordance with Rule 457(c) of the Securities Act solely for the purpose of calculating the registration fee. The Proposed Maximum Offering Price per Share and the Proposed Maximum Aggregate Offering Price are based upon the average of the high and low prices of the Registrant's common stock as reported on the Nasdaq Global Market on May 6, 2021, which date is within five business days prior to filing this Registration Statement.
(3)
Represents additional shares of the Registrant's common stock that became available for issuance under the 2019 Plan, pursuant to the evergreen provision of the 2019 Plan.
(4)
Represents additional shares of the Registrant's common stock that became available for issuance under the 2019 ESPP, pursuant to the evergreen provision of the 2019 ESPP.
Proposed sales to take place as soon after the effective date of the Registration Statement as awards granted under the above-named plans are granted, exercised and/or distributed.
EXPLANATORY NOTE
This Registration Statement on Form S-8 is being filed with the Securities and Exchange Commission for the purpose of registering an additional 1,260,665 shares of common stock of  Exagen Inc. (the "Registrant") issuable or which may become issuable under the Exagen Inc. 2019 Incentive Award Plan (the "2019 Plan") and the Exagen Inc. 2019 Employee Stock Purchase Plan (the "2019 ESPP") pursuant to the evergreen provision of such plans.
Pursuant to General Instruction E on Form S-8, the contents of the prior registration statement on Form S-8, File No. 333-233878, previously filed with respect to the 2019 Plan and 2019 ESPP, are incorporated into this Registration Statement by reference to the extent not modified or superseded hereby or by any subsequently filed document, which is incorporated by reference herein or therein.
PART I
INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS
The documents containing the information specified in Part I of Form S-8 will be sent or given to participants as specified by Rule 428(b)(1) of the Securities Act. These documents and the documents incorporated by reference into this Registration Statement pursuant to Item 3 of Part II of this Registration Statement, taken together, constitute a prospectus that meets the requirements of Section 10(a) of the Securities Act.
PART II
INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
In this Registration Statement, Exagen Inc. is sometimes referred to as "Registrant," "we," "us" or "our."
Item 3. Incorporation of Documents by Reference
The Securities and Exchange Commission ("SEC") allows us to "incorporate by reference" the information we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this Registration Statement, and later information filed with the SEC will update and supersede this information. We hereby incorporate by reference into this Registration Statement the following documents previously filed with the SEC:
•
The Registrant's Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 16, 2021 and Amendment No. 1 to the Registrant's Annual Report on Form 10-K/A for the year ended December 31, 2020, filed with the SEC on April 1, 2021;
•
The Registrant's Current Reports on Form 8-K filed with the SEC on March 22, 2021 and March 23, 2021;
•
The Registrant's Definitive Proxy Statement on Schedule 14A, filed with the SEC on April 27, 2021; and
•
The description of the Registrant's common stock set forth in the Registrant's registration statement on Form 8-A12B (Registration No. 001-39049), filed by the Registrant with the SEC under Section 12(b) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), on September 13, 2019, including any amendments or reports filed for the purpose of updating such description.
In addition, all documents filed by the Registrant pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the filing of this registration statement and prior to the filing of a post-effective amendment which
indicates that all securities offered hereby have been sold or which de-registers all securities then remaining unsold shall be deemed to be incorporated by reference into this registration statement and to be a part hereof from the date of filing such documents, except as to specific sections of such statements as set forth therein. Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this registration statement to the extent that a statement contained herein or in any other subsequently filed document which also is incorporated or deemed to be incorporated by reference herein modifies or supersedes such statement. Any statement contained herein shall be deemed to be modified or superseded for purposes of this registration statement to the extent that a statement contained in any subsequently filed document which also is incorporated or deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this registration statement.
Under no circumstances shall any information furnished under Item 2.02 or 7.01 of Form 8-K be deemed incorporated herein by reference unless such Form 8-K expressly provides to the contrary.
EXHIBIT INDEX
Incorporated by Reference
Exhibit Number
Exhibit Description
Form
File No.
Exhibit
Exhibit Filing Date
Filed/Furnished Herewith
3.1
Form of Amended and Restated Certificate of Incorporation.
8-K
001-39049
3.1
9/23/2019
3.2
Form of Amended Restated Bylaws.
8-K
001-39049
3.1
3/22/2021
4.1
Specimen stock certificate evidencing the shares of common stock.
S-1/A
333-233446
4.1
9/9/2019
5.1
Opinion of Latham & Watkins LLP.
X
10.1
Exagen Inc. 2019 Incentive Award Plan.
S-1/A
333-233446
10.3
9/9/2019
10.2
Form of Option Agreement under Exagen Inc. 2019 Incentive Award Plan
.
S-1/A
333-233446
10.4
9/9/2019
10.3
Form of Restricted Stock Unit Agreement under Exagen Inc. 2019 Incentive Award Plan.
10-K
001-39049
10.5
3/16/2021
10.4
Exagen Inc. 2019 Employee Stock Purchase Plan
.
S-1/A
333-233446
10.5
9/9/2019
23.1
Consent of BDO USA, LLP, independent registered public accounting firm.
X
23.2
Consent of Latham & Watkins LLP (included in Exhibit 5.1).
X
24.1
Power of Attorney (see signature page)
X
SIGNATURES
Pursuant to the requirements of the Securities Act, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Vista, State of California, on May 11, 2021.
EXAGEN INC.
by:
/s/ Fortunato Ron Rocca
Fortunato Ron Rocca
President and Chief Executive Officer
(Principal Executive Officer)
Each person whose signature appears below hereby constitutes and appoints Fortunato Ron Rocca and Kamal Adawi, and each of them singly (with full power to each of them to act alone), his attorneys-in-fact, each with the full power of substitution, for him in any and all capacities, to sign this registration statement, and any amendments thereto (including post-effective amendments), and to file the same, with all exhibits thereto and other documents in connection therewith, with the SEC, hereby ratifying and confirming all that each of said attorneys-in-fact, or his substitute or substitutes, may do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act, this registration statement has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated.
Signature
Title
Date
/s/ Fortunato Ron Rocca
President, Chief Executive Officer and Director
May 11, 2021
Fortunato Ron Rocca
(Principal Executive Officer)
/s/ Kamal Adawi
Chief Financial Officer and Corporate Secretary
May 11, 2021
Kamal Adawi
(Principal Financial and Accounting Officer)
/s/ Brian Birk
Chairman of the Board of Directors
May 11, 2021
Brian Birk
/s/ Jeff Elliott
Director
May 11, 2021
Jeff Elliott
/s/ Wendy S. Johnson
Director
May 11, 2021
Wendy S. Johnson
/s/ Tina S. Nova, Ph.D.
Director
May 11, 2021
Tina S. Nova, Ph.D.
/s/ Ebetuel Pallares, Ph.D.
Director
May 11, 2021
Ebetuel Pallares, Ph.D.
/s/ Bruce C. Robertson, Ph.D.
Director
May 11, 2021
Bruce C. Robertson, Ph.D.
/s/ James L.L. Tullis
Director
May 11, 2021
James L.L. Tullis