<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): March 15, 2006

                         MERRILL LYNCH DEPOSITOR, INC.
                    (ON BEHALF OF PPLUS TRUST SERIES CMT-1)
             (Exact name of registrant as specified in its charter)

          DELAWARE                 001-32142                    13-3891329
      (State or other         (Commission File #)           (I. R. S. Employer
      jurisdiction of                                       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

                      INFORMATION TO BE INCLUDED IN 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 (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>


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 PPLUS Trust Certificates
                  Series CMT-1 on March 15, 2006.


                        For information with respect to the underlying
                  securities held by PPLUS Trust Series CMT-1, please refer to
                  Comcast Corporation's (Commission file number 000-50093)
                  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 guarantors' and underlying securities
                  issuer have filed electronically with the SEC.
<PAGE>

                        Although we have no reason to believe the information
                  concerning the underlying securities, the underlying
                  guarantees, the underlying securities issuer or the underlying
                  securities guarantors contained in the underlying securities
                  issuer's or the underlying securities guarantors' 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 or the underlying securities guarantors
                  (including, without limitation, no investigation as to their
                  respective financial condition or creditworthiness), the
                  underlying securities or the underlying guarantees has been
                  made. You should obtain and evaluate the same information
                  concerning the underlying securities issuer and the underlying
                  securities guarantors as you would obtain and evaluate if you
                  were investing directly in the underlying securities and the
                  underlying guarantees or in other securities issued by the
                  underlying securities issuer or the underlying securities
                  guarantors. There can be no assurance that events affecting
                  the underlying securities, the underlying guarantees, the
                  underlying securities issuer or the underlying securities
                  guarantors 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.

                  (c) Exhibits.

                      99.1    Trustee's report in respect of the March 15, 2006
                              distribution to holders of the PPLUS Trust
                              Certificates Series CMT-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: March 30, 2006                By:      /s/ Stephan Kuppenheimer
                                              ------------------------------
                                    Name:    Stephan Kuppenheimer
                                    Title:   President

<PAGE>

                                  EXHIBIT INDEX


          99.1    Trustee's report in respect of the March 15, 2006 distribution
                  to holders of the PPLUS Trust Certificates Series CMT-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): March 15, 2006

                         MERRILL LYNCH DEPOSITOR, INC.
                    (ON BEHALF OF PPLUS TRUST SERIES CMT-1)
             (Exact name of registrant as specified in its charter)

          DELAWARE                 001-32142                    13-3891329
      (State or other         (Commission File #)           (I. R. S. Employer
      jurisdiction of                                       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

                      INFORMATION TO BE INCLUDED IN 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 (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))
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 PPLUS Trust Certificates
                  Series CMT-1 on March 15, 2006.

                        For information with respect to the underlying
                  securities held by PPLUS Trust Series CMT-1, please refer to
                  Comcast Corporation's (Commission file number 000-50093)
                  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 guarantors' and underlying securities
                  issuer have filed electronically with the SEC.
Although we have no reason to believe the information
                  concerning the underlying securities, the underlying
                  guarantees, the underlying securities issuer or the underlying
                  securities guarantors contained in the underlying securities
                  issuer's or the underlying securities guarantors' 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 or the underlying securities guarantors
                  (including, without limitation, no investigation as to their
                  respective financial condition or creditworthiness), the
                  underlying securities or the underlying guarantees has been
                  made. You should obtain and evaluate the same information
                  concerning the underlying securities issuer and the underlying
                  securities guarantors as you would obtain and evaluate if you
                  were investing directly in the underlying securities and the
                  underlying guarantees or in other securities issued by the
                  underlying securities issuer or the underlying securities
                  guarantors. There can be no assurance that events affecting
                  the underlying securities, the underlying guarantees, the
                  underlying securities issuer or the underlying securities
                  guarantors 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.

                  (c) Exhibits.

                      99.1    Trustee's report in respect of the March 15, 2006
                              distribution to holders of the PPLUS Trust
                              Certificates Series CMT-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: March 30, 2006                By:      /s/ Stephan Kuppenheimer
                                              ------------------------------
                                    Name:    Stephan Kuppenheimer
                                    Title:   President
EXHIBIT INDEX

          99.1    Trustee's report in respect of the March 15, 2006 distribution
                  to holders of the PPLUS Trust Certificates Series CMT-1.