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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">UNITED
      STATES</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
      AND EXCHANGE 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">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"><strong>FORM
      8-K</strong></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 PURSUANT </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">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
      30, 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: 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;TBW
      Mortgage-Backed Trust Series
      2006-4&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</u></font></div>
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      Entity)</font></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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      Suisse First Boston Mortgage Securities
      Corp.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</u></font></div>
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      Bean &amp; Whitaker Mortgage
      Corp.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</u></font></div>
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    <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;Credit
      Suisse First Boston Mortgage Securities
      Corp.&#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="left"><br></div>
    <div>
      <table cellpadding="0" cellspacing="0" width="100%">

          <tr>
            <td valign="top" width="27%" style="border-bottom: medium none;">
              <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;Delaware&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</u></font></div>
            </td>
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            </td>
            <td valign="top" width="27%" style="border-bottom: medium none;">
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            </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 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>
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                Number)</font></div>
            </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>
      <table cellpadding="0" cellspacing="0" width="100%">

          <tr>
            <td valign="top" width="27%" style="border-bottom: medium none;">
              <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">11
                Madison Avenue</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"><u>New
                York, NY </u></font></div>
            </td>
            <td valign="top" width="27%" style="border-bottom: medium none;">&#160;</td>
            <td valign="bottom" width="27%" style="border-bottom: medium none;">
              <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;10010&#160;&#160;&#160;&#160;&#160;&#160;</u></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 Executive Offices)</font></div>
            </td>
            <td valign="top" width="27%">&#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="justify">&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; 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) 325-2000</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;&#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;&#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="left"><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">[
      ]
      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">[
      ]
      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">[
      ]
      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">[
      ]
      Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange
      Act
      (17 CFR 240.13e-4(c))</font></div><br>
    <div id="PGBRK" style="MARGIN-LEFT: 0pt; WIDTH: 100%; 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">&#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: 36pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left">&#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">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: 72pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Item
      8.01. Other Events.</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: 72pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">McKee
      Nelson LLP has been retained by this Registrant as counsel for its Registration
      Statement on Form S-3 (Commission File No. 333-135481) in connection with
      various transactions. Legal opinions by McKee Nelson LLP to be incorporated
      into
      the Registration Statement are attached hereto as Exhibit 5.1, Exhibit 8.1
      and
      Exhibit 23.1.</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">Item
      9.01. </font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>Financial
      Statements and Exhibits</u></font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">.</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%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 36pt;">&#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">(a)</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">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%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 36pt;">&#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">(b)</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">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%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 36pt;">&#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">(c)</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">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 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">(d)<font id="TAB2" style="LETTER-SPACING: 9pt">&#160;&#160;&#160;</font></font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">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%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 45pt;">&#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">&#160;&#160;5.1</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">Opinion
                of McKee Nelson LLP as to legality (including consent of such
                firm).</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: 45pt;">&#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">&#160;&#160;8.1</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">Opinion
                of McKee Nelson LLP as to certain tax matters (including consent
                of such
                firm included in Exhibit&#160;5.1).</font></div>
            </td>
          </tr>

      </table>
    </div>
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            <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">23.1</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">Consent
                of McKee Nelson LLP (included in Exhibit
                5.1).</font></div>
            </td>
          </tr>

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    </div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify">&#160;</div><br>
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        <div id="GLFTR" style="WIDTH: 100%" align="left">&#160;</div>
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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>
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      <div id="HDR">
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    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; 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: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="center"><font id="TAB1" style="MARGIN-LEFT: 54pt"></font><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
      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>
      <table align="center" border="0" cellpadding="0" cellspacing="0" id="hangingindent" width="100%">

          <tr valign="top" style="line-height: 1.25;">
            <td style="width: 36pt;">&#160;</td>
            <td style="width: 36pt;">&#160;</td>
            <td style="width: 36pt;">&#160;</td>
            <td style="width: 36pt;">&#160;</td>
            <td style="width: 36pt;">&#160;</td>
            <td style="width: 36pt;">&#160;</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">CREDIT
                SUISSE FIRST BOSTON MORTGAGE SECURITIES
                CORP.</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>&#160;</div>
    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font id="TAB1" style="MARGIN-LEFT: 36pt"></font><font id="TAB1" style="MARGIN-LEFT: 36pt"></font><font id="TAB1" style="MARGIN-LEFT: 36pt"></font><font id="TAB1" style="MARGIN-LEFT: 36pt"></font><font id="TAB1" style="MARGIN-LEFT: 36pt"></font><font id="TAB1" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">By:
      </font><font id="TAB2" style="COLOR: black; LETTER-SPACING: 27pt">&#160;</font><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>/s/
      Kevin Steele<font id="TAB2" style="LETTER-SPACING: 9pt">&#160;&#160;&#160;</font>&#160;<font id="TAB2" style="LETTER-SPACING: 9pt">&#160;&#160;&#160;</font>&#160;<font id="TAB2" style="LETTER-SPACING: 9pt">&#160;&#160;&#160;</font>&#160;<font id="TAB2" style="LETTER-SPACING: 9pt">&#160;&#160;&#160;</font>&#160;</u></font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 234pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Name:
      Kevin Steele </font></div>
    <div style="DISPLAY: block; MARGIN-LEFT: 234pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Title:
      Vice President</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="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Dated:
      August 30, 2006</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="left"><br></div><br>
    <div id="PGBRK" style="MARGIN-LEFT: 0pt; WIDTH: 100%; 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">&#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><br>
    <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>EXHIBIT
      INDEX</u></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="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 align="left">
      <table border="0" cellpadding="0" cellspacing="0" width="100%">

          <tr>
            <td align="justify" valign="top" width="12%" style="border-bottom: medium none;">
              <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="justify"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"><u>Exhibit
                No.</u></font></div>
            </td>
            <td align="justify" valign="top" width="73%" style="border-bottom: medium none;">
              <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>Description</u></font></div>
            </td>
            <td align="justify" valign="top" width="15%" style="border-bottom: medium none;">
              <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>Page
                No.</u></font></div>
            </td>
          </tr>
          <tr>
            <td align="left" valign="top" width="12%" style="border-bottom: medium none;">&#160;</td>
            <td align="left" valign="top" width="73%" style="border-bottom: medium none;">&#160;</td>
            <td align="left" valign="top" width="15%" style="border-bottom: medium none;">&#160;</td>
          </tr>
          <tr>
            <td align="left" valign="top" width="12%" style="border-bottom: medium none;">
              <div style="DISPLAY: block; MARGIN-LEFT: 18pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">5.1</font></div>
            </td>
            <td align="left" colspan="2" valign="top" width="88%" style="border-bottom: medium none;">
              <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">Opinion
                of McKee Nelson LLP as to legality (including consent of such
                firm).</font></div>
            </td>
          </tr>
          <tr>
            <td align="left" valign="top" width="12%" style="border-bottom: medium none;">
              <div style="DISPLAY: block; MARGIN-LEFT: 18pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">8.1</font></div>
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                of McKee Nelson LLP as to certain tax matters (including consent
                of such
                firm included in Exhibit&#160;&#160;5.1).</font></div>
            </td>
          </tr>
          <tr>
            <td align="left" valign="top" width="12%" style="border-bottom: medium none;">
              <div style="DISPLAY: block; MARGIN-LEFT: 18pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">23.1</font></div>
            </td>
            <td align="left" colspan="2" valign="top" width="88%" style="border-bottom: medium none;">
              <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">Consent
                of McKee Nelson LLP (included in Exhibit 5.1).
</font></div>
            </td>
          </tr>

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    <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; LINE-HEIGHT: 1.25; MARGIN-RIGHT: 0pt" align="left">&#160;</div>
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{"company-data": {"conformed-name": "TBW Mortgage-Backed Trust Series 2006-4", "cik": "0001372827", "assigned-sic": "6189", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "333-135481-01", "film-number": "061064899"}, "business-address": {"street1": "11 MADISON AVENUE", "city": "NEW YORK", "state": "NY", "zip": "10010", "phone": "2123252000"}, "mail-address": {"street1": "11 MADISON AVENUE", "city": "NEW YORK", "state": "NY", "zip": "10010"}}
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)
August
      30, 2006
TBW
      Mortgage-Backed Trust Series
      2006-4
(Issuing
      Entity)
Credit
      Suisse First Boston Mortgage Securities
      Corp.
(Exact
      Name of Depositor as Specified in its Charter)
Taylor,
      Bean & Whitaker Mortgage
      Corp.
(Exact
      Name of Sponsor as Specified in its Charter)
Credit
      Suisse First Boston Mortgage Securities
      Corp.
(Exact
      Name of Registrant as Specified in its Charter)
Delaware
333-135481
13-3320910
(State
                or Other Jurisdiction
Of
                Incorporation)
(Commission
File
                Number)
(I.R.S.
                Employer
Identification
                No.)
11
                Madison Avenue
New
                York, NY
10010
(Address
                of Principal Executive Offices)
(Zip
                Code)
Registrant's
      telephone number, including area code: (212) 325-2000
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:
[
      ]
      Written communications pursuant to Rule 425 under the Securities Act (17 CFR
      230.425)
[
      ]
      Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR
      240.14a-12)
[
      ]
      Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange
      Act
      (17 CFR 240.14d-2(b))
[
      ]
      Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange
      Act
      (17 CFR 240.13e-4(c))
Item
      8.01.
Other
      Events
Item
      8.01. Other Events.
McKee
      Nelson LLP has been retained by this Registrant as counsel for its Registration
      Statement on Form S-3 (Commission File No. 333-135481) in connection with
      various transactions. Legal opinions by McKee Nelson LLP to be incorporated
      into
      the Registration Statement are attached hereto as Exhibit 5.1, Exhibit 8.1
      and
      Exhibit 23.1.
Item
      9.01.
Financial
      Statements and Exhibits
.
(a)
Not
                applicable.
(b)
Not
                applicable.
(c)
Not
                applicable.
(d)
Exhibits:
5.1
Opinion
                of McKee Nelson LLP as to legality (including consent of such
                firm).
8.1
Opinion
                of McKee Nelson LLP as to certain tax matters (including consent
                of such
                firm included in Exhibit 5.1).
23.1
Consent
                of McKee Nelson LLP (included in Exhibit
                5.1).
SIGNATURES
Pursuant
      to the requirements of the Securities Exchange Act of 1934, the registrant
      duly
      caused this report to be signed on its behalf by the undersigned hereunto duly
      authorized.
CREDIT
                SUISSE FIRST BOSTON MORTGAGE SECURITIES
                CORP.
By:
/s/
      Kevin Steele
Name:
      Kevin Steele
Title:
      Vice President
Dated:
      August 30, 2006
EXHIBIT
      INDEX
Exhibit
                No.
Description
Page
                No.
5.1
Opinion
                of McKee Nelson LLP as to legality (including consent of such
                firm).
8.1
Opinion
                of McKee Nelson LLP as to certain tax matters (including consent
                of such
                firm included in Exhibit  5.1).
23.1
Consent
                of McKee Nelson LLP (included in Exhibit 5.1).