<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): May 15, 2006

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

         DELAWARE             001-32018                    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

                      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
                  TWC-1 on May 15, 2006.

                           For information with respect to the underlying
                  securities held by PPLUS Trust Series TWC-1, please refer to
                  Time Warner Inc.'s (Commission file number 001-15062) 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.

<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
                  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 financial condition or
                  creditworthiness) or of 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 your investment were directly
                  in the underlying securities and the underlying guarantees or
                  in other securities issued by the underlying securities issuer
                  or the underlying guarantors. There can be no assurance that
                  events affecting the underlying securities and the underlying
                  guarantees or 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.

         (d)      Exhibits.

                  99.1     Trustee's report in respect of the May 15, 2006
                           distribution to holders of the PPLUS Trust
                           Certificates Series TWC-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: 06/05/2006                 By: /s/ Zvi Gillon
                                     ----------------------------------------
                                 Name:  Zvi Gillon
                                 Title: Vice President


<PAGE>

                                  EXHIBIT INDEX


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

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

         DELAWARE             001-32018                    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

                      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
                  TWC-1 on May 15, 2006.

                           For information with respect to the underlying
                  securities held by PPLUS Trust Series TWC-1, please refer to
                  Time Warner Inc.'s (Commission file number 001-15062) 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, the underlying
                  guarantees, the underlying securities issuer or the underlying
                  securities guarantors contained in 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 financial condition or
                  creditworthiness) or of 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 your investment were directly
                  in the underlying securities and the underlying guarantees or
                  in other securities issued by the underlying securities issuer
                  or the underlying guarantors. There can be no assurance that
                  events affecting the underlying securities and the underlying
                  guarantees or 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.

         (d)      Exhibits.

                  99.1     Trustee's report in respect of the May 15, 2006
                           distribution to holders of the PPLUS Trust
                           Certificates Series TWC-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: 06/05/2006                 By: /s/ Zvi Gillon
                                     ----------------------------------------
                                 Name:  Zvi Gillon
                                 Title: Vice President
EXHIBIT INDEX

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