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    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 12pt; FONT-FAMILY: Times New Roman">SECURITIES
      AND EXCHANGE COMMISSION</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Washington,
      D.C. 20549</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 12pt; FONT-FAMILY: Times New Roman">FORM
      8-K</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">CURRENT
      REPORT</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">PURSUANT
      TO SECTION 13 OR 15(d) OF THE</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">SECURITIES
      EXCHANGE ACT OF 1934</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Date
      of
      Report (Date of earliest event reported)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">August
      10, 2006</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 36pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">STRUCTURED
      ASSET SECURITIES CORPORATION (as Depositor under the Trust Agreement dated
      as of
      July 1, 2006, providing for the issuance of Thornburg Mortgage Securities Trust
      2006-4, Mortgage Loan Pass-Through Certificates, Series 2006-4)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;Thornburg
      Mortgage Securities Trust
      2006-4&#160;&#160;&#160;&#160;&#160;&#160;</u></font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(Exact
      Name of Issuing Entity as Specified in its Charter)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>&#160;&#160;
      Structured Asset Securities
      Corporation&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</u></font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(Exact
      Name of Registrant as Specified in its Charter)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>&#160;&#160;Thornburg
      Mortgage Home Loans, Inc.&#160;&#160;&#160;&#160;&#160;</u></font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(Exact
      Name of Sponsor as Specified in its Charter)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div>
      <table cellpadding="0" cellspacing="0" width="100%">

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              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Delaware</font></div>
            </td>
            <td width="5%">&#160;</td>
            <td valign="top" width="27%" style="border-bottom: black thin solid;">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">333-129480</font></div>
            </td>
            <td width="5%">&#160;</td>
            <td valign="top" width="27%" style="border-bottom: black thin solid;">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">74-2440850</font></div>
            </td>
          </tr>
          <tr>
            <td valign="top" width="27%">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(State
                or Other Jurisdiction</font></div>
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Of
                Incorporation)</font></div>
            </td>
            <td width="5%">&#160;</td>
            <td valign="top" width="27%">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(Commission</font></div>
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">File
                Number)</font></div>
            </td>
            <td width="5%">&#160;</td>
            <td valign="top" width="27%">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(I.R.S.
                Employer</font></div>
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Identification
                No.)</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div align="left">
      <table cellpadding="0" cellspacing="0" width="100%">

          <tr>
            <td valign="top" width="27%" style="border-bottom: black thin solid;">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">745
                Seventh Avenue, 7th Floor</font></div>
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">New
                York, NY</font></div>
            </td>
            <td valign="top" width="37%">&#160;</td>
            <td valign="top" width="27%" style="border-bottom: black thin solid;">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center">&#160;</div>
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">10019</font></div>
            </td>
          </tr>
          <tr>
            <td valign="top" width="27%">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(Address
                of Principal </font></div>
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Executive
                Offices)</font></div>
            </td>
            <td valign="top" width="37%">&#160;</td>
            <td valign="top" width="27%">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(Zip
                Code)</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><br></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Registrant&#8217;s
      telephone number, including area code: (212) 526-7000</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;
      No
      Change&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</u></font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(Former
      Name or Former Address, if Changed Since Last Report)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><br></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">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:</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><font style="DISPLAY: inline; FONT-FAMILY: Wingdings">o</font>
      Written communications
      pursuant to Rule 425 under the Securities Act (17 CFR 230.425)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><font face="Wingdings">o</font>
      Soliciting material pursuant to Rule 14a-12 under the
      Exchange Act (17 CFR 240.14a-12)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><font face="Wingdings">o</font>
      Pre-commencement communications pursuant to Rule
      14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><font face="Wingdings">o</font>
      Pre-commencement communications pursuant to Rule
      13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left">&#160;</div>
    <div id="PGBRK" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">
      <div id="FTR">
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        <div style="WIDTH: 100%; TEXT-ALIGN: center">&#160;</div>
        <div style="WIDTH: 100%; TEXT-ALIGN: center">
          <hr style="COLOR: black" noshade size="2">
        </div>
      </div>
      <div id="HDR">
        <div id="GLHDR" style="WIDTH: 100%" align="right">&#160;</div>
      </div>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div><br>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Item
      8.01. </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>Other
      Events</u></font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">The
      Registrant registered issuances of Thornburg Mortgage Securities Trust 2006-4
      Mortgage Loan Pass-Through Certificates, Series 2006-4 on a delayed or
      continuous basis pursuant to Rule 415 under the Securities Act of 1933, as
      amended (the &#8220;Act&#8221;), by a Registration Statement on Form S-3 (Registration File
      No. </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">333-129480</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">)
      (the
&#8220;Registration Statement&#8221;). Pursuant to the Registration Statement, the
      Registrant issued in aggregate principal amount of $1,649,002,100 the Class
      A-1,
      Class A-2A, Class A-2B, Class A-2C, Class A-X, Class R, Class B-1, Class B-2
      and
      Class B-3 Thornburg Mortgage Securities Trust 2006-4, Mortgage Loan Pass-Through
      Certificates, Series 2006-4 (the &#8220;Public Certificates&#8221;) on August 10, 2006. The
      Public Certificates were offered pursuant to the Prospectus, dated June 2,
      2006,
      as supplemented by the Prospectus Supplement, dated August 8, 2006 (the
&#8220;Prospectus Supplement&#8221;), a form of which was filed as an exhibit to the
      Registration Statement.</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">This
      Current Report on Form 8-K includes a copy of the Trust Agreement (as defined
      below) and other operative agreements executed in connection with the issuance
      of the Certificates. The Certificates were issued pursuant to a Trust Agreement
      (the &#8220;Trust Agreement&#8221;), attached hereto as </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>Exhibit
      4.1</u></font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">,
      dated
      as of July 1, 2006, among Structured Asset Securities Corporation, as depositor,
      Wilmington Trust Company, as Delaware trustee, LaSalle Bank National
      Association, as trustee and custodian, </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Thornburg
      Mortgage Home Loans, Inc.,</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">
      as
      seller and Wells Fargo Bank, N.A., as master servicer and securities
      administrator. The &#8220;Certificates&#8221; consist of the following classes: Class A-1,
      Class A-2A, Class A-2B, Class A-2C, Class A-X, Class R, Class B-1, Class B-2,
      Class B-3, Class B-4, Class B-5 and Class B-6. The Certificates evidence all
      of
      the beneficial ownership interest in a trust fund (the &#8220;Trust Fund&#8221;) that
      consists primarily of two pools of adjustable rate and hybrid, first lien,
      residential mortgage loans (the &#8220;Mortgage Loans&#8221;) with an aggregate outstanding
      principal balance of $1,663,981,912 as of July 1, 2006, together with certain
      other assets. Capitalized terms used herein and not otherwise defined shall
      have
      the meanings assigned to them in the Trust Agreement.</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left">&#160;</div>
    <div id="PGBRK" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">
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        <div style="WIDTH: 100%; TEXT-ALIGN: center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">2</font></div>
        <div style="WIDTH: 100%; TEXT-ALIGN: center">
          <hr style="COLOR: black" noshade size="2">
        </div>
      </div>
      <div id="HDR">
        <div id="GLHDR" style="WIDTH: 100%" align="right">&#160;</div>
      </div>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 72pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Item
      9.01. Financial Statements and Exhibits</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

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            </td>
            <td align="left" style="width: 27pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(a)</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Not
                applicable.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 36pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

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            <td style="width: 45pt;">
            </td>
            <td align="left" style="width: 27pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(b)</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Not
                applicable.</font></div>
            </td>
          </tr>

      </table>
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    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

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            <td style="width: 45pt;">
            </td>
            <td align="left" style="width: 27pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(c)</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Not
                applicable.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 36pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 45pt;">
            </td>
            <td align="left" style="width: 27pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(d)</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Exhibits:</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 72pt;">
            </td>
            <td align="left" style="width: 36pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">4.1</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Trust
                Agreement, dated as of July 1, 2006, among Structured Asset Securities
                Corporation, as depositor, Wilmington Trust Company, as Delaware
                trustee,
                LaSalle Bank National Association (&#8220;LaSalle&#8221;), as trustee and custodian,
                </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Thornburg
                Mortgage Home Loans, Inc. </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(&#8220;Thornburg&#8221;)</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">,</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">
                as
                seller and Wells Fargo Bank, N.A. (&#8220;Wells Fargo&#8221;), as master servicer and
                securities administrator.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 72pt;">
            </td>
            <td align="left" style="width: 36pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">4.2</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Mortgage
                Loan Purchase Agreement, dated as of July 1, 2006, between </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Thornburg,</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">
                as
                seller, and Structured Asset Securities Corporation, as purchaser.
                </font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 72pt;">&#160;</td>
            <td style="width: 36pt;">
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.1</font></div>
            </td>
            <td>
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Auction
                Administration Agreement, dated as of August 10, 2006, between Credit
                Suisse International and Wells
                Fargo</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 72pt;">&#160;</td>
            <td style="width: 36pt;">
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.2</font></div>
            </td>
            <td>
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">ISDA
                Master Agreement, Schedule to ISDA Master Agreement, Schedule and
                swap
                confirmation, each dated as of August 10, 2006, between Credit Suisse
                International and Wells Fargo</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 72pt;">&#160;</td>
            <td style="width: 36pt;">
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.3</font></div>
            </td>
            <td>
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Cap
                agreement, dated as of August 10, 2006, between The Royal Bank of
                Scotland
                plc and Thornburg Mortgage Securities Trust 2006-4, relating to the
                Class
                A-1 Certificates.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 72pt;">&#160;</td>
            <td style="width: 36pt;">
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.4</font></div>
            </td>
            <td>
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Cap
                agreement, dated as of August 10, 2006, between The Royal Bank of
                Scotland
                plc and Thornburg Mortgage Securities Trust 2006-4, relating to the
                Class
                A-2A, Class A-2B and Class A-2C
                Certificates.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 72pt;">&#160;</td>
            <td style="width: 36pt;">
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.5</font></div>
            </td>
            <td>
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(a)
                Servicing Agreement, dated as of March 1, 2002, among Thornburg,
                as seller
                and servicer and Wells Fargo, as master servicer, as amended by the
                Amendment to Servicing Agreement, dated as of December 1, 2002, and
                as
                amended by the Second Amendment to Servicing Agreement, dated as
                of
                January 1, 2006, and (b) the Subservicing Acknowledgement Agreement,
                dated
                as of March 1, 2002, between Thornburg, as servicer, and Cenlar FSB,
                as
                sub-servicer (&#8220;Cenlar&#8221;), as amended by the Amendment to Subservicing
                Acknowledgement Agreement, dated as of December 1, 2002, and by the
                Second
                Amendment to Subservicing Acknowledgement Agreement, dated as of
                January
                1, 2006, including the related Transfer Notice, dated July 26, 2006,
                from
                Thornburg, as seller, to Thornburg, as servicer, and Cenlar, as
                sub-servicer.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 72pt;">&#160;</td>
            <td style="width: 36pt;">
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.6</font></div>
            </td>
            <td>
              <div style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Reconstituted
                Servicing Agreement, dated as of July 1, 2006, by and among Thornburg,
                Wells Fargo, as servicer, Thornburg Mortgage Securities Trust 2006-4,
                and
                acknowledged by Wells Fargo, as master servicer, relating to the
                Second
                Amended and Restated Master Seller&#8217;s Warranties and Servicing Agreement
                dated as of May 1, 2006, between Bank of America, National Association
                (&#8220;B
                of A&#8221;) and Wells Fargo, as amended by the Assignment, Assumption and
                Recognition Agreement dated as of July 25, 2006, among B of A, Wells
                Fargo
                and Thornburg.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div id="PGBRK" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">
      <div id="FTR">
        <div id="GLFTR" style="WIDTH: 100%" align="left">&#160;</div>
      </div>
      <div id="PN" style="PAGE-BREAK-AFTER: always">
        <div style="WIDTH: 100%; TEXT-ALIGN: center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">3</font></div>
        <div style="WIDTH: 100%; TEXT-ALIGN: center">
          <hr style="COLOR: black" noshade size="2">
        </div>
      </div>
      <div id="HDR">
        <div id="GLHDR" style="WIDTH: 100%" align="right">&#160;</div>
      </div>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div><br>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><strong>SIGNATURES</strong></font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">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></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">
      <table align="center" bgcolor="#ffffff" border="0" cellpadding="0" cellspacing="0" width="100%">

          <tr valign="top" bgcolor="#ffffff">
            <td width="50%"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">&#160;</font></td>
            <td width="1%"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">&#160;</font></td>
            <td width="49%"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">&#160;</font></td>
          </tr>
          <tr valign="top" bgcolor="#ffffff">
            <td><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">&#160;</font></td>
            <td colspan="2"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">STRUCTURED
              ASSET
              SECURITIES CORPORATION</font></td>
          </tr>
          <tr valign="top" bgcolor="#ffffff">
            <td><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">&#160;<br>&#160;</font></td>
            <td><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">&#160;<br>&#160;</font></td>
            <td><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">&#160;<br>&#160;</font></td>
          </tr>
          <tr valign="top" bgcolor="#ffffff">
            <td>&#160;</td>
            <td><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">By:&#160;&#160;</font></td>
            <td><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">/s/&#160;Mary
              Stone</font></td>
          </tr>
          <tr valign="top" bgcolor="#ffffff">
            <td colspan="2"><font style="FONT-FAMILY: " size="1">&#160;</font></td>
            <td align="left">
              <hr style="COLOR: black" align="left" noshade size="2" width="80%"><font size="2">Name:
              Mary Stone</font></td>
          </tr>
          <tr valign="top" bgcolor="#ffffff">
            <td colspan="2"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">&#160;</font></td>
            <td><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: ">Title:
              Vice President</font></td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 216pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left">&#160;</div>
    <div><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Dated:
      August 10, 2006</font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div id="PGBRK" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">
      <div id="FTR">
        <div id="GLFTR" style="WIDTH: 100%" align="left">&#160;</div>
      </div>
      <div id="PN" style="PAGE-BREAK-AFTER: always">
        <div style="WIDTH: 100%; TEXT-ALIGN: center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">4</font></div>
        <div style="WIDTH: 100%; TEXT-ALIGN: center">
          <hr style="COLOR: black" noshade size="2">
        </div>
      </div>
      <div id="HDR">
        <div id="GLHDR" style="WIDTH: 100%" align="right">&#160;</div>
      </div>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>EXHIBIT
      INDEX</u></font><br></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><br></div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>Exhibit
              No.</u></font></td>
            <td align="left">
              <div align="justify"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>Description</u></font></div>
            </td>
          </tr>

      </table>
    </div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">4.1</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Trust
                Agreement, dated as of July 1, 2006, among Structured Asset Securities
                Corporation., as depositor, Wilmington Trust Company, as Delaware
                trustee,
                LaSalle Bank National Association (&#8220;LaSalle&#8221;), as trustee and custodian,
                </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Thornburg
                Mortgage Home Loans, Inc. </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(&#8220;Thornburg&#8221;)</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">,</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">
                as
                seller and Wells Fargo Bank, N.A. (&#8220;Wells Fargo&#8221;), as master servicer and
                securities administrator.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">4.2</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Mortgage
                Loan Purchase Agreement, dated as of July 1, 2006, between </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Thornburg,</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">
                as
                seller, and Structured Asset Securities Corporation, as purchaser.
                </font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.1</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Auction
                Administration Agreement, dated as of August 10, 2006 between Credit
                Suisse International and Wells
                Fargo.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.2</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">ISDA
                Master Agreement, Schedule to ISDA Master Agreement, Schedule and
                swap
                confirmation, each dated as of August 10, 2006, between Credit Suisse
                International and Wells Fargo.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.3</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Cap
                agreement, dated as of August 10, 2006, between The Royal Bank of
                Scotland
                plc and Thornburg Mortgage Securities Trust 2006-4, relating to the
                Class
                A-1 Certificates.</font></div>
            </td>
          </tr>

      </table>
    </div>
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    <div>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%" style="MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt">

          <tr valign="top" style="line-height: 1.25;">
            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.4</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Cap
                agreement, dated as of August 10, 2006, between The Royal Bank of
                Scotland
                plc and Thornburg Mortgage Securities Trust 2006-4, relating to the
                Class
                A-2A, Class A-2B and Class A-2C
                Certificates.</font></div>
            </td>
          </tr>

      </table>
    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div>
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          <tr valign="top" style="line-height: 1.25;">
            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.5</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">(a)
                Servicing Agreement, dated as of March 1, 2002, among Thornburg,
                as seller
                and servicer and Wells Fargo, as master servicer, as amended by the
                Amendment to Servicing Agreement, dated as of December 1, 2002, and
                as
                amended by the Second Amendment to Servicing Agreement, dated as
                of
                January 1, 2006, and (b) the Subservicing Acknowledgement Agreement,
                dated
                as of March 1, 2002, between Thornburg, as servicer, and Cenlar FSB,
                as
                sub-servicer (&#8220;Cenlar&#8221;), as amended by the Amendment to Subservicing
                Acknowledgement Agreement, dated as of December 1, 2002, and by the
                Second
                Amendment to Subservicing Acknowledgement Agreement, dated as of
                January
                1, 2006, including the related Transfer Notice, dated July 26, 2006,
                from
                Thornburg, as seller, to Thornburg, as servicer, and Cenlar, as
                sub-servicer.</font></div>
            </td>
          </tr>

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    </div>
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            <td align="left" style="width: 81pt;"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">99.6</font></td>
            <td align="left">
              <div align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Reconstituted
                Servicing Agreement, dated as of July 1, 2006, by and among Thornburg,
                Wells Fargo, as servicer, Thornburg Mortgage Securities Trust 2006-4,
                and
                acknowledged by Wells Fargo, as master servicer, relating to the
                Second
                Amended and Restated Master Seller&#8217;s Warranties and Servicing Agreement
                dated as of May 1, 2006, between Bank of America, National Association
                (&#8220;B
                of A&#8221;) and Wells Fargo, as amended by the Assignment, Assumption and
                Recognition Agreement dated as of July 25, 2006, among B of A, Wells
                Fargo
                and Thornburg.</font></div>
            </td>
          </tr>

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{"company-data": {"conformed-name": "Thornburg Mortgage Securities Trust 2006-4", "cik": "0001369387", "assigned-sic": "6189", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "333-129480-26", "film-number": "061057069"}, "business-address": {"street1": "745 7TH AVENUE", "city": "NEW YORK", "state": "NY", "zip": "10019", "phone": "2125267000"}, "mail-address": {"street1": "745 7TH AVENUE", "city": "NEW YORK", "state": "NY", "zip": "10019"}}
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)
August
      10, 2006
STRUCTURED
      ASSET SECURITIES CORPORATION (as Depositor under the Trust Agreement dated
      as of
      July 1, 2006, providing for the issuance of Thornburg Mortgage Securities Trust
      2006-4, Mortgage Loan Pass-Through Certificates, Series 2006-4)
Thornburg
      Mortgage Securities Trust
      2006-4
(Exact
      Name of Issuing Entity as Specified in its Charter)
Structured Asset Securities
      Corporation
(Exact
      Name of Registrant as Specified in its Charter)
Thornburg
      Mortgage Home Loans, Inc.
(Exact
      Name of Sponsor as Specified in its Charter)
Delaware
333-129480
74-2440850
(State
                or Other Jurisdiction
Of
                Incorporation)
(Commission
File
                Number)
(I.R.S.
                Employer
Identification
                No.)
745
                Seventh Avenue, 7th Floor
New
                York, NY
10019
(Address
                of Principal
Executive
                Offices)
(Zip
                Code)
Registrant's
      telephone number, including area code: (212) 526-7000
No
      Change
(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
      8.01.
Other
      Events
The
      Registrant registered issuances of Thornburg Mortgage Securities Trust 2006-4
      Mortgage Loan Pass-Through Certificates, Series 2006-4 on a delayed or
      continuous basis pursuant to Rule 415 under the Securities Act of 1933, as
      amended (the "Act"), by a Registration Statement on Form S-3 (Registration File
      No.
333-129480
)
      (the
"Registration Statement"). Pursuant to the Registration Statement, the
      Registrant issued in aggregate principal amount of $1,649,002,100 the Class
      A-1,
      Class A-2A, Class A-2B, Class A-2C, Class A-X, Class R, Class B-1, Class B-2
      and
      Class B-3 Thornburg Mortgage Securities Trust 2006-4, Mortgage Loan Pass-Through
      Certificates, Series 2006-4 (the "Public Certificates") on August 10, 2006. The
      Public Certificates were offered pursuant to the Prospectus, dated June 2,
      2006,
      as supplemented by the Prospectus Supplement, dated August 8, 2006 (the
"Prospectus Supplement"), a form of which was filed as an exhibit to the
      Registration Statement.
This
      Current Report on Form 8-K includes a copy of the Trust Agreement (as defined
      below) and other operative agreements executed in connection with the issuance
      of the Certificates. The Certificates were issued pursuant to a Trust Agreement
      (the "Trust Agreement"), attached hereto as
Exhibit
      4.1
,
      dated
      as of July 1, 2006, among Structured Asset Securities Corporation, as depositor,
      Wilmington Trust Company, as Delaware trustee, LaSalle Bank National
      Association, as trustee and custodian,
Thornburg
      Mortgage Home Loans, Inc.,
as
      seller and Wells Fargo Bank, N.A., as master servicer and securities
      administrator. The "Certificates" consist of the following classes: Class A-1,
      Class A-2A, Class A-2B, Class A-2C, Class A-X, Class R, Class B-1, Class B-2,
      Class B-3, Class B-4, Class B-5 and Class B-6. The Certificates evidence all
      of
      the beneficial ownership interest in a trust fund (the "Trust Fund") that
      consists primarily of two pools of adjustable rate and hybrid, first lien,
      residential mortgage loans (the "Mortgage Loans") with an aggregate outstanding
      principal balance of $1,663,981,912 as of July 1, 2006, together with certain
      other assets. Capitalized terms used herein and not otherwise defined shall
      have
      the meanings assigned to them in the Trust Agreement.
2
Item
      9.01. Financial Statements and Exhibits
(a)
Not
                applicable.
(b)
Not
                applicable.
(c)
Not
                applicable.
(d)
Exhibits:
4.1
Trust
                Agreement, dated as of July 1, 2006, among Structured Asset Securities
                Corporation, as depositor, Wilmington Trust Company, as Delaware
                trustee,
                LaSalle Bank National Association ("LaSalle"), as trustee and custodian,
Thornburg
                Mortgage Home Loans, Inc.
("Thornburg")
,
as
                seller and Wells Fargo Bank, N.A. ("Wells Fargo"), as master servicer and
                securities administrator.
4.2
Mortgage
                Loan Purchase Agreement, dated as of July 1, 2006, between
Thornburg,
as
                seller, and Structured Asset Securities Corporation, as purchaser.
99.1
Auction
                Administration Agreement, dated as of August 10, 2006, between Credit
                Suisse International and Wells
                Fargo
99.2
ISDA
                Master Agreement, Schedule to ISDA Master Agreement, Schedule and
                swap
                confirmation, each dated as of August 10, 2006, between Credit Suisse
                International and Wells Fargo
99.3
Cap
                agreement, dated as of August 10, 2006, between The Royal Bank of
                Scotland
                plc and Thornburg Mortgage Securities Trust 2006-4, relating to the
                Class
                A-1 Certificates.
99.4
Cap
                agreement, dated as of August 10, 2006, between The Royal Bank of
                Scotland
                plc and Thornburg Mortgage Securities Trust 2006-4, relating to the
                Class
                A-2A, Class A-2B and Class A-2C
                Certificates.
99.5
(a)
                Servicing Agreement, dated as of March 1, 2002, among Thornburg,
                as seller
                and servicer and Wells Fargo, as master servicer, as amended by the
                Amendment to Servicing Agreement, dated as of December 1, 2002, and
                as
                amended by the Second Amendment to Servicing Agreement, dated as
                of
                January 1, 2006, and (b) the Subservicing Acknowledgement Agreement,
                dated
                as of March 1, 2002, between Thornburg, as servicer, and Cenlar FSB,
                as
                sub-servicer ("Cenlar"), as amended by the Amendment to Subservicing
                Acknowledgement Agreement, dated as of December 1, 2002, and by the
                Second
                Amendment to Subservicing Acknowledgement Agreement, dated as of
                January
                1, 2006, including the related Transfer Notice, dated July 26, 2006,
                from
                Thornburg, as seller, to Thornburg, as servicer, and Cenlar, as
                sub-servicer.
99.6
Reconstituted
                Servicing Agreement, dated as of July 1, 2006, by and among Thornburg,
                Wells Fargo, as servicer, Thornburg Mortgage Securities Trust 2006-4,
                and
                acknowledged by Wells Fargo, as master servicer, relating to the
                Second
                Amended and Restated Master Seller's Warranties and Servicing Agreement
                dated as of May 1, 2006, between Bank of America, National Association
                ("B
                of A") and Wells Fargo, as amended by the Assignment, Assumption and
                Recognition Agreement dated as of July 25, 2006, among B of A, Wells
                Fargo
                and Thornburg.
3
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.
STRUCTURED
              ASSET
              SECURITIES CORPORATION
By:
/s/ Mary
              Stone
Name:
              Mary Stone
Title:
              Vice President
Dated:
      August 10, 2006
4
EXHIBIT
      INDEX
Exhibit
              No.
Description
4.1
Trust
                Agreement, dated as of July 1, 2006, among Structured Asset Securities
                Corporation., as depositor, Wilmington Trust Company, as Delaware
                trustee,
                LaSalle Bank National Association ("LaSalle"), as trustee and custodian,
Thornburg
                Mortgage Home Loans, Inc.
("Thornburg")
,
as
                seller and Wells Fargo Bank, N.A. ("Wells Fargo"), as master servicer and
                securities administrator.
4.2
Mortgage
                Loan Purchase Agreement, dated as of July 1, 2006, between
Thornburg,
as
                seller, and Structured Asset Securities Corporation, as purchaser.
99.1
Auction
                Administration Agreement, dated as of August 10, 2006 between Credit
                Suisse International and Wells
                Fargo.
99.2
ISDA
                Master Agreement, Schedule to ISDA Master Agreement, Schedule and
                swap
                confirmation, each dated as of August 10, 2006, between Credit Suisse
                International and Wells Fargo.
99.3
Cap
                agreement, dated as of August 10, 2006, between The Royal Bank of
                Scotland
                plc and Thornburg Mortgage Securities Trust 2006-4, relating to the
                Class
                A-1 Certificates.
99.4
Cap
                agreement, dated as of August 10, 2006, between The Royal Bank of
                Scotland
                plc and Thornburg Mortgage Securities Trust 2006-4, relating to the
                Class
                A-2A, Class A-2B and Class A-2C
                Certificates.
99.5
(a)
                Servicing Agreement, dated as of March 1, 2002, among Thornburg,
                as seller
                and servicer and Wells Fargo, as master servicer, as amended by the
                Amendment to Servicing Agreement, dated as of December 1, 2002, and
                as
                amended by the Second Amendment to Servicing Agreement, dated as
                of
                January 1, 2006, and (b) the Subservicing Acknowledgement Agreement,
                dated
                as of March 1, 2002, between Thornburg, as servicer, and Cenlar FSB,
                as
                sub-servicer ("Cenlar"), as amended by the Amendment to Subservicing
                Acknowledgement Agreement, dated as of December 1, 2002, and by the
                Second
                Amendment to Subservicing Acknowledgement Agreement, dated as of
                January
                1, 2006, including the related Transfer Notice, dated July 26, 2006,
                from
                Thornburg, as seller, to Thornburg, as servicer, and Cenlar, as
                sub-servicer.
99.6
Reconstituted
                Servicing Agreement, dated as of July 1, 2006, by and among Thornburg,
                Wells Fargo, as servicer, Thornburg Mortgage Securities Trust 2006-4,
                and
                acknowledged by Wells Fargo, as master servicer, relating to the
                Second
                Amended and Restated Master Seller's Warranties and Servicing Agreement
                dated as of May 1, 2006, between Bank of America, National Association
                ("B
                of A") and Wells Fargo, as amended by the Assignment, Assumption and
                Recognition Agreement dated as of July 25, 2006, among B of A, Wells
                Fargo
                and Thornburg.
5