<PAGE>

                       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): December 15, 2006

                          MERRILL LYNCH DEPOSITOR, INC.
                 (on behalf of PREFERREDPLUS TRUST SERIES CTR-1)
             (Exact name of registrant as specified in its charter)

         Delaware                001-16747                 13-3891329
     (State or other           (Commission             (I. R. S. Employer
     jurisdiction  of           File Number)           Identification No.)
      incorporation)

            World Financial Center,                          10080
              New York, New York                          (Zip Code)
             (Address of principal
              executive offices)

                           --------------------------


       Registrant's telephone number, including area code: (212) 449-1000

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 (see General Instruction A.2.):

[  ]  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))
<PAGE>

                      INFORMATION TO BE INCLUDED IN REPORT


SECTION 1.        REGISTRANT'S BUSINESS AND OPERATIONS

                  Not applicable.

SECTION 2.        FINANCIAL INFORMATION

                  Not applicable.

SECTION 3.        SECURITIES AND TRADING MARKETS

                  Not applicable.

SECTION 4.        MATTERS RELATED TO ACCOUNTANTS AND FINANCIAL STATEMENTS

                  Not applicable.

SECTION 5.        CORPORATE GOVERNANCE AND MANAGEMENT

                  Not applicable.

SECTION 6.        ASSET-BACKED SECURITIES

                  Not Applicable.

SECTION 7.        REGULATION FD

                  Not applicable.

SECTION 8.        OTHER EVENTS

         ITEM 8.01           OTHER EVENTS

                    99.1     Distribution to holders of the PreferredPLUS Trust
                             Certificates Series CTR-1 on December 15, 2006.

                                    For information with respect to the
                             underlying securities held by PreferredPLUS Trust
                             Series CTR-1, please refer to Cooper Tire & Rubber
                             Company's (Commission file number 001-04329)
                             periodic reports, including annual reports on Form
                             10-K, quarterly reports on Form 10-Q and current
                             reports on Form 8-K, and other information on file
                             with the Securities and Exchange Commission (the
                             "SEC"). You can read and copy these reports and
                             other information at the public reference
                             facilities maintained by the SEC at Room 1580, 100
                             F Street, NE, Washington, D.C. 20549. You may
                             obtain copies of this material for a fee by writing
                             to the SEC's Public Reference Section of the SEC at
                             100 F Street, NE, Washington, D.C. 20549. You may
                             obtain information about the operation of the
                             Public Reference Room by calling the SEC at
                             1-800-SEC-0330. You can also access some of this
                             information electronically by means of the SEC's
                             website on the Internet at http://www.sec.gov,
                             which contains reports, proxy and information
                             statements and other information that the
                             underlying securities issuer has filed
                             electronically with the SEC.

                                    Although we have no reason to believe the
                             information concerning the underlying securities or
                             the underlying securities issuer contained in the
                             underlying securities issuer's Exchange Act reports
                             is not reliable, neither the depositor nor the
                             trustee participated in the preparation of such
                             documents or made any due diligence inquiry with
                             respect to the information provided therein. No
                             investigation with respect to the underlying
                             securities issuer (including, without limitation,
                             no investigation as to its financial condition or
                             creditworthiness) or of the underlying securities
                             has been made. You should obtain and evaluate the
                             same information concerning the underlying
                             securities issuer as you would obtain and evaluate
                             if you were investing directly in the underlying
                             securities or in other securities issued by the
                             underlying securities issuer. There can be no
                             assurance that events affecting the underlying
                             securities or the underlying securities issuer have
                             not occurred or have not yet been publicly
                             disclosed which would affect the accuracy or
                             completeness of the publicly available documents
                             described above.
<PAGE>


SECTION 9.        FINANCIAL STATEMENTS AND EXHIBITS

         ITEM 9.01           FINANCIAL STATEMENTS AND EXHIBITS


                  (a)        Financial statements of business acquired.

                             Not Applicable.

                  (b)        Pro forma financial information.

                             Not Applicable.

                  (c)        Shell company transactions.

                             Not Applicable.

                  (d) Exhibits.

                      99.1   Trustee's report in respect of the December 15,
                             2006 distribution to holders of the PreferredPLUS
                             Trust Certificates Series CTR-1.

<PAGE>

                                   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.

                                       MERRILL LYNCH DEPOSITOR, INC.

         Date: 12/19/2006              By:      /s/ Jason Liddell
                                                --------------------------------
                                       Name:    Jason Liddell
                                       Title:   Vice-President

<PAGE>

                                  EXHIBIT INDEX


                      99.1   Trustee's report in respect of the December 15,
                             2006 distribution to holders of the PreferredPLUS
                             Trust Certificates Series CTR-1.
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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): December 15, 2006

                          MERRILL LYNCH DEPOSITOR, INC.
                 (on behalf of PREFERREDPLUS TRUST SERIES CTR-1)
             (Exact name of registrant as specified in its charter)

         Delaware                001-16747                 13-3891329
     (State or other           (Commission             (I. R. S. Employer
     jurisdiction  of           File Number)           Identification No.)
      incorporation)

            World Financial Center,                          10080
              New York, New York                          (Zip Code)
             (Address of principal
              executive offices)

                           --------------------------

       Registrant's telephone number, including area code: (212) 449-1000

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 (see General Instruction A.2.):

[  ]  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))
INFORMATION TO BE INCLUDED IN REPORT

SECTION 1.        REGISTRANT'S BUSINESS AND OPERATIONS

                  Not applicable.

SECTION 2.        FINANCIAL INFORMATION

                  Not applicable.

SECTION 3.        SECURITIES AND TRADING MARKETS

                  Not applicable.

SECTION 4.        MATTERS RELATED TO ACCOUNTANTS AND FINANCIAL STATEMENTS

                  Not applicable.

SECTION 5.        CORPORATE GOVERNANCE AND MANAGEMENT

                  Not applicable.

SECTION 6.        ASSET-BACKED SECURITIES

                  Not Applicable.

SECTION 7.        REGULATION FD

                  Not applicable.

SECTION 8.        OTHER EVENTS

         ITEM 8.01           OTHER EVENTS

                    99.1     Distribution to holders of the PreferredPLUS Trust
                             Certificates Series CTR-1 on December 15, 2006.

                                    For information with respect to the
                             underlying securities held by PreferredPLUS Trust
                             Series CTR-1, please refer to Cooper Tire & Rubber
                             Company's (Commission file number 001-04329)
                             periodic reports, including annual reports on Form
                             10-K, quarterly reports on Form 10-Q and current
                             reports on Form 8-K, and other information on file
                             with the Securities and Exchange Commission (the
                             "SEC"). You can read and copy these reports and
                             other information at the public reference
                             facilities maintained by the SEC at Room 1580, 100
                             F Street, NE, Washington, D.C. 20549. You may
                             obtain copies of this material for a fee by writing
                             to the SEC's Public Reference Section of the SEC at
                             100 F Street, NE, Washington, D.C. 20549. You may
                             obtain information about the operation of the
                             Public Reference Room by calling the SEC at
                             1-800-SEC-0330. You can also access some of this
                             information electronically by means of the SEC's
                             website on the Internet at http://www.sec.gov,
                             which contains reports, proxy and information
                             statements and other information that the
                             underlying securities issuer has filed
                             electronically with the SEC.

                                    Although we have no reason to believe the
                             information concerning the underlying securities or
                             the underlying securities issuer contained in the
                             underlying securities issuer's Exchange Act reports
                             is not reliable, neither the depositor nor the
                             trustee participated in the preparation of such
                             documents or made any due diligence inquiry with
                             respect to the information provided therein. No
                             investigation with respect to the underlying
                             securities issuer (including, without limitation,
                             no investigation as to its financial condition or
                             creditworthiness) or of the underlying securities
                             has been made. You should obtain and evaluate the
                             same information concerning the underlying
                             securities issuer as you would obtain and evaluate
                             if you were investing directly in the underlying
                             securities or in other securities issued by the
                             underlying securities issuer. There can be no
                             assurance that events affecting the underlying
                             securities or the underlying securities issuer have
                             not occurred or have not yet been publicly
                             disclosed which would affect the accuracy or
                             completeness of the publicly available documents
                             described above.
SECTION 9.        FINANCIAL STATEMENTS AND EXHIBITS

         ITEM 9.01           FINANCIAL STATEMENTS AND EXHIBITS

                  (a)        Financial statements of business acquired.

                             Not Applicable.

                  (b)        Pro forma financial information.

                             Not Applicable.

                  (c)        Shell company transactions.

                             Not Applicable.

                  (d) Exhibits.

                      99.1   Trustee's report in respect of the December 15,
                             2006 distribution to holders of the PreferredPLUS
                             Trust Certificates Series CTR-1.
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.

                                       MERRILL LYNCH DEPOSITOR, INC.

         Date: 12/19/2006              By:      /s/ Jason Liddell
                                                --------------------------------
                                       Name:    Jason Liddell
                                       Title:   Vice-President
EXHIBIT INDEX

                      99.1   Trustee's report in respect of the December 15,
                             2006 distribution to holders of the PreferredPLUS
                             Trust Certificates Series CTR-1.