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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">UNITED STATES</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">SECURITIES AND EXCHANGE COMMISSION</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Washington, D.C. 20549</font></b></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">FORM&nbsp;8-K</font></b></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">CURRENT REPORT</font></b></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">Pursuant to Section&nbsp;13 OR 15(d)&nbsp;of The</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">Securities Exchange Act of 1934</font></b></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Date of Report (Date of earliest event reported): <b>June&nbsp;28, 2013</b></font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">CoreSite Realty Corporation</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Exact name of registrant as specified in its charter)</font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Maryland</font></b></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">001-34877</font></b></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">27-1925611</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(State or other jurisdiction<br>   of incorporation)</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Commission<br>   File Number)</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(IRS Employer<br>   Identification No.)</font></p>    </td>   </tr>  </table>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">1050 17th Street, Suite&nbsp;800<br>   Denver, CO</font></b></p>    </td>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">80265</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Address of principal executive offices)</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Zip Code)</font></p>    </td>   </tr>  </table>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Registrant&#146;s telephone number, including area code:<b> (866)&nbsp;777-2673</b></font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">N/A</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Former name or former address, if changed since last report.)</font></p>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Check the appropriate box below if the Form&nbsp;8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font><font size="2" style="font-size:10.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Written communications pursuant to Rule&nbsp;425 under the Securities Act (17 CFR 230.425)</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font><font size="2" style="font-size:10.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Soliciting material pursuant to Rule&nbsp;14a-12 under the Exchange Act (17 CFR 240.14a-12)</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font><font size="2" style="font-size:10.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Pre-commencement communications pursuant to Rule&nbsp;14d-2(b)&nbsp;under the Exchange Act (17 CFR 240.14d-2(b))</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font><font size="2" style="font-size:10.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Pre-commencement communications pursuant to Rule&nbsp;13e-4(c)&nbsp;under the Exchange Act (17 CFR 240.13e-4(c))</font></p>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 1.01.</font></b><font size="2" style="font-size:10.0pt;">&nbsp;&nbsp; <b>Entry into a Material Definitive Agreement.</b></font></p>
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<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The description of the Joinder Agreements described below under Item 2.03 is incorporated in this Item 1.01 by reference. Copies of the Joinder Agreements are filed as Exhibits 10.1 and 10.2 to this Form&nbsp;8-K and are incorporated herein by reference.</font></p>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 2.03.</font></b><font size="2" style="font-size:10.0pt;">&nbsp;&nbsp; <b>Creation of a Direct Financial Obligation or an Obligation Under an Off-Balance Sheet Arrangement of a Registrant.</b></font></p>
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<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">As previously disclosed, on January&nbsp;3, 2013, CoreSite, L.P. (the operating partnership of CoreSite Realty Corporation), as parent borrower, and certain subsidiary co-borrowers entered into a second amended and restated unsecured revolving credit facility with a group of lenders for which KeyBank National Association acts as the administrative agent (the &#147;Credit Agreement&#148;). Under the terms of the Credit Agreement, the borrowers thereunder may, at their option, increase the aggregate amount of borrowings under the revolving credit facility to increase the total commitments by $145.0 million, to $500.0 million, without the consent of any lenders not participating in such increase, subject to certain customary conditions and lenders committing to provide the increase in funding (the &#147;Accordion&#148;).</font></p>
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<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Effective as of June&nbsp;28, 2013, the borrowers under the Credit Agreement partially exercised the Accordion to increase the aggregate commitments under the Credit Agreement by $50.0 million (the &#147;Accordion Exercise&#148;). As a result of the Accordion Exercise, the borrowing capacity under the Credit Agreement increased from $355.0 million to $405.0 million. All other terms of the Credit Agreement remain unchanged. In order to provide the additional commitments in connection with the Accordion Exercise, two additional lenders (the &#147;Additional Members&#148;) executed joinder agreements (the &#147;Joinder Agreements&#148;) effective June&nbsp;28, 2013, relating to the Credit Agreement, to include the Additional Members in the lending group thereunder, thereby increasing commitments under the Credit Agreement to $405.0 million.</font></p>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item&nbsp;9.01 Financial Statements and Exhibits.</font></b></p>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(d)&nbsp;Exhibits</font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Description&nbsp;of&nbsp;Exhibit</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">10.1</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Joinder   Agreement, dated as of June&nbsp;28, 2013, among CoreSite, L.P., a Delaware   limited partnership, the subsidiary borrowers party thereto, Toronto Dominion   (Texas) LLC and KeyBank National Association, as administrative agent for the   lenders thereunder.</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">10.2</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Joinder   Agreement, dated as of June&nbsp;28, 2013, among CoreSite, L.P., a Delaware   limited partnership, the subsidiary borrowers party thereto, Wells Fargo   Bank, National Association and KeyBank National Association, as   administrative agent for the lenders thereunder.</font></p>    </td>   </tr>  </table>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2<a name="PB_2_174201_7056"></a></font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">SIGNATURES</font></b></p>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.</font></p>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">CORESITE REALTY CORPORATION</font></b></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Date:   June&nbsp;28, 2013</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">/s/   Jeffrey S. Finnin</font></b></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Jeffrey S. Finnin</font></b></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title:</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Chief Financial Officer</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3<a name="PB_3_174612_5335"></a></font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">EXHIBIT&nbsp;INDEX</font></b></p>
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<p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Exhibit</font></b><b><font size="1" style="font-size:8.0pt;font-weight:bold;"><br>    </font></b><b><font size="1" style="font-size:8.0pt;font-weight:bold;">No.</font></b></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">10.1</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Joinder   Agreement, dated as of June&nbsp;28, 2013, among CoreSite, L.P., a Delaware   limited partnership, the subsidiary borrowers party thereto, Toronto Dominion   (Texas) LLC and KeyBank National Association, as administrative agent for the   lenders thereunder.</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">10.2</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Joinder   Agreement, dated as of June&nbsp;28, 2013, among CoreSite, L.P., a Delaware   limited partnership, the subsidiary borrowers party thereto, Wells Fargo   Bank, National Association and KeyBank National Association, as   administrative agent for the lenders thereunder.</font></p>    </td>   </tr>  </table>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4<a name="PB_4_174727_5796"></a></font></p>
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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 8-K
CURRENT REPORT
Pursuant to Section 13 OR 15(d) of The
Securities Exchange Act of 1934
Date of Report (Date of earliest event reported):
June 28, 2013
CoreSite Realty Corporation
(Exact name of registrant as specified in its charter)
Maryland
001-34877
27-1925611
(State or other jurisdiction
of incorporation)
(Commission
File Number)
(IRS Employer
Identification No.)
1050 17th Street, Suite 800
Denver, CO
80265
(Address of principal executive offices)
(Zip Code)
Registrant's telephone number, including area code:
(866) 777-2673
N/A
(Former name or former address, if changed since last report.)
Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:
o
Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
o
Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
o
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
o
Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
Item 1.01.
Entry into a Material Definitive Agreement.
The description of the Joinder Agreements described below under Item 2.03 is incorporated in this Item 1.01 by reference. Copies of the Joinder Agreements are filed as Exhibits 10.1 and 10.2 to this Form 8-K and are incorporated herein by reference.
Item 2.03.
Creation of a Direct Financial Obligation or an Obligation Under an Off-Balance Sheet Arrangement of a Registrant.
As previously disclosed, on January 3, 2013, CoreSite, L.P. (the operating partnership of CoreSite Realty Corporation), as parent borrower, and certain subsidiary co-borrowers entered into a second amended and restated unsecured revolving credit facility with a group of lenders for which KeyBank National Association acts as the administrative agent (the "Credit Agreement"). Under the terms of the Credit Agreement, the borrowers thereunder may, at their option, increase the aggregate amount of borrowings under the revolving credit facility to increase the total commitments by $145.0 million, to $500.0 million, without the consent of any lenders not participating in such increase, subject to certain customary conditions and lenders committing to provide the increase in funding (the "Accordion").
Effective as of June 28, 2013, the borrowers under the Credit Agreement partially exercised the Accordion to increase the aggregate commitments under the Credit Agreement by $50.0 million (the "Accordion Exercise"). As a result of the Accordion Exercise, the borrowing capacity under the Credit Agreement increased from $355.0 million to $405.0 million. All other terms of the Credit Agreement remain unchanged. In order to provide the additional commitments in connection with the Accordion Exercise, two additional lenders (the "Additional Members") executed joinder agreements (the "Joinder Agreements") effective June 28, 2013, relating to the Credit Agreement, to include the Additional Members in the lending group thereunder, thereby increasing commitments under the Credit Agreement to $405.0 million.
Item 9.01 Financial Statements and Exhibits.
(d) Exhibits
Exhibit No.
Description of Exhibit
10.1
Joinder   Agreement, dated as of June 28, 2013, among CoreSite, L.P., a Delaware   limited partnership, the subsidiary borrowers party thereto, Toronto Dominion   (Texas) LLC and KeyBank National Association, as administrative agent for the   lenders thereunder.
10.2
Joinder   Agreement, dated as of June 28, 2013, among CoreSite, L.P., a Delaware   limited partnership, the subsidiary borrowers party thereto, Wells Fargo   Bank, National Association and KeyBank National Association, as   administrative agent for the lenders thereunder.
2
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
CORESITE REALTY CORPORATION
Date:   June 28, 2013
By:
/s/   Jeffrey S. Finnin
Name:
Jeffrey S. Finnin
Title:
Chief Financial Officer
3
EXHIBIT INDEX
Exhibit
No.
10.1
Joinder   Agreement, dated as of June 28, 2013, among CoreSite, L.P., a Delaware   limited partnership, the subsidiary borrowers party thereto, Toronto Dominion   (Texas) LLC and KeyBank National Association, as administrative agent for the   lenders thereunder.
10.2
Joinder   Agreement, dated as of June 28, 2013, among CoreSite, L.P., a Delaware   limited partnership, the subsidiary borrowers party thereto, Wells Fargo   Bank, National Association and KeyBank National Association, as   administrative agent for the lenders thereunder.
4