SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    ----------
                                    FORM 10-K

                        FOR ANNUAL AND TRANSITION REPORTS
                     PURSUANT TO SECTIONS 13 OR 15(D) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


(Mark One)
[X]      ANNUAL REPORT PURSUANT TO SECTION 13 or 15(D) OF THE SECURITIES
         EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2005
                          -----------------

                                       OR

[  ]     TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
         EXCHANGE  ACT OF 1934

For the transition period from __________ to __________

                  COMMISSION FILE NUMBERS 001-16443, 333-64879


                            MS STRUCTURED ASSET CORP.
                                  ON BEHALF OF
                            SATURNS TRUST NO. 2001-4
             (Exact name of registrant as specified in its charter)


                       Delaware                            13-4026700
          (State or other jurisdiction of      (IRS Employer Identification No.)
          incorporation or organization)


                     1585 BROADWAY, SECOND FLOOR             10036
                     NEW YORK, NEW YORK
                     ATTENTION: MADHU PHILIPS
                     (Address of principal executive        (Zip Code)
                     office)

                   Registrant's telephone number,         (212) 761-2520
                   including area code:

               Securities registered pursuant to Section 12(b) of the Act:

          Title of Each Class                         Name of Each Exchange on
                                                          Which Registered

          SATURNS BELLSOUTH DEBENTURE-BACKED           NEW YORK STOCK EXCHANGE
          SERIES 2001-4 CALLABLE UNITS




           Securities registered pursuant to Section 12(g) of the Act:

                                      NONE


<PAGE>
         Indicate by check mark if the registrant is a well-known seasoned
issuer, as defined in Rule 405 of the Securities Act.  Yes        No  X
                                                          -----     -----

         Indicate by check mark if the registrant is not required to file
reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.
Yes        No  X
   -----     -----

         Indicate by check mark whether registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days. Yes  X     No
                                             -----     -----

         Indicate by check mark if disclosure of delinquent filers pursuant to
Item 405 of Regulation S-K is not contained herein, and will not be contained,
to the best of registrant's knowledge, in definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K or any
amendment to this Form 10-K. [ ]

         Indicate by check mark whether the registrant is a large accelerated
filer, an accelerated filer, or a non-accelerated filer. See definition of
"accelerated filer and large accelerated filer" in Rule 12b-2 of the Exchange
Act.

(Check one):

Large accelerated filer       Accelerated filer       Non-accelerated filer  X
                        ---                     ---                         ---

         Indicate by check mark whether the registrant is a shell company (as
defined in Rule 12b-2 of the Act).  Yes        No  X
                                       -----     -----

         All of the common stock of the registrant is held by Morgan Stanley.

         Indicate by check mark whether the registrant has filed all documents
and reports required to be filed by Section 12, 13 or 15(d) of the Securities
Exchange Act of 1934 subsequent to the distribution of securities under a plan
confirmed by a court. Yes        No
                          -----     -----

         As of February 20, 2006, 1,000 shares of common stock, par value $1.00
per share, were outstanding.

                      DOCUMENTS INCORPORATED BY REFERENCE:

  The distribution reports to security holders filed on Form 8-K during the
Fiscal Year in lieu of reports on Form 10-Q.

                                Introductory Note

The Registrant is the depositor under the trust agreements for it various
SATURNS Units listed on the New York Stock Exchange. The Units do not represent
obligations of or interests in the Depositor. Pursuant to staff administrative
positions established in various no-action letters, see e.g. Corporate Asset
Backed Corporation (available August 9, 1995), the Registrant is not required to
respond to various items of Form 10-K. Such items are designated herein as "Not
applicable." Distribution reports detailing receipts and distributions by each
trust are filed shortly after each distribution date on Form 8-K in lieu of
reports on Form 10-Q.

The underlying security issuer or guarantor, as applicable, of the securities
held by each of the trusts is subject to the informational requirements of the
Exchange Act. The underlying security issuer or guarantor, as applicable,
currently files reports, proxy statements and other information with the SEC.
For information regarding such underlying security issuer or guarantor, you
should refer to such reports. These periodic, current and other reports and
other information can be inspected and copied at the public reference facilities
maintained by the SEC at Room 1024, 100 F Street, N.E., Washington, D.C. 20549.
Copies of those materials can be obtained by making a written request to the
SEC, Public Reference Section, 100 F Street, N.E., Washington, D.C. 20549, at
prescribed rates. The SEC also maintains a website on the internet at
http://www.sec.gov at which users can view and download copies of reports,
proxy, information statements and other information filed electronically. In
addition, those reports and other information may also be obtained from the
underlying security issuer by making a request to the underlying security
issuer. The trust, the trustee, the Registrant, and their affiliates have not
verified, have not undertaken to verify, and will not verify, the content of any
such reports or information. The name and the central index key (CIK) for each
underlying security issuer or guarantor is set forth below:

<TABLE>
<CAPTION>
          Trust               Underlying Security Issuer                 CIK
                                     or Guarantor
          <S>                 <C>                                     <C>
          2001-4              Cummins Inc.                            0000026712
</TABLE>
<PAGE>



                                     PART I

ITEM 1.  BUSINESS

         Not Applicable

ITEM 2.  PROPERTIES

         Not Applicable

ITEM 3.  LEGAL PROCEEDINGS

         None

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

         None


                                    PART II

ITEM 5.  MARKET FOR REGISTRANT'S COMMON EQUITY AND RELATED STOCKHOLDER MATTERS

The Units issued by the SATURNS trusts listed below representing investors'
interest in such trust are represented by one or more physical certificates
registered in the name of Cede & Co., the nominee of The Depository Trust
Company. These Units are listed on the New York Stock Exchange:

SATURNS Trust No. 2001-4 (Cummins Engine Company Debenture-Backed)

ITEM 6.  SELECTED FINANCIAL DATA

         Not Applicable


ITEM 7.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
         RESULTS OF OPERATIONS

         Not Applicable

ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

         Not Applicable

ITEM 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

         Not Applicable


<PAGE>



ITEM 9.  CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
         FINANCIAL DISCLOSURE

         None

ITEM 9A. CONTROLS AND PROCEDURES

         Not Applicable

                                    PART III

ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

         Not Applicable

ITEM 11. EXECUTIVE COMPENSATION

         Not Applicable


Item 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

         None

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

         None

ITEM 14. PRINCIPAL ACCOUNTING FEES AND SERVICES

         Not Applicable

                                     PART IV

ITEM 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K

         (a) The following documents are filed as part of this Report: None

         (b) Reports on Form 8-K:

See Table Below:


<PAGE>



<TABLE>
<CAPTION>
SATURNS Trust No.:     Closing Date     Payment Dates     Form 8-K Filing Dates (Not Trust
                                                          Agreement Filings in connection with
                                                          Closing Date)

                                                          For FY 2005

<S>                    <C>              <C>               <C>
2001-4                 6/4/01           March 1 and       March 4, 2005 and September 7, 2005
                                        September 1
</TABLE>

         (c) Exhibits:

Exhibit 31.1      Rule 13a-14(d) Certification
Exhibit 31.2      Trustee Compliance Certification

The trust covered by this annual report was formed prior to June 30, 2003 and
there is no requirement in the trust agreement for the preparation of a report
by an independent public accountant regarding the trustee's compliance with its
obligations.

         (d) Not applicable


<PAGE>



                                   SIGNATURES

         Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the Registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized.



         Date:  March 29, 2006

                                                    MS STRUCTURED ASSET CORP.
                                                    (Registrant)



                                                    By:      /s/ Madhu Philips
                                                       -------------------------
                                                    Name:    Madhu Philips
                                                    Title:   Vice President


<PAGE>



                                                                    Exhibit 31.1
                                  CERTIFICATION

I, Madhu Philips, certify that:

1.    I have reviewed this annual report on Form 10-K, and all reports on Form
8-K containing distribution or servicing reports filed in respect of periods
included in the year covered by this annual report, of MS Structured Asset Corp.
on behalf of SATURNS Trust No. 2001-4;

2.    Based on my knowledge, the information in these reports, taken as a whole,
does not contain any untrue statement of a material fact or omit to state a
material fact necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading as of the
last day of the period covered by this annual report;

3.    Based on my knowledge, the distribution or servicing information required
to be provided to the depositor by the trustee under the pooling and servicing,
or similar, agreement, for inclusion in these reports is included in these
reports; and

4.    I am responsible for reviewing the activities performed by the depositor
and the trustee under the pooling and servicing, or similar, agreement and based
upon my knowledge and the annual compliance review required under that
agreement, and except as disclosed in the reports, the depositor and trustee
have each fulfilled its obligations under that agreement.

In giving the certifications above, I have reasonably relied on information
provided to me by the following unaffiliated parties: LaSalle Bank National
Association and its officers and agents.



                                                    By:      /s/ Madhu Philips
                                                       -------------------------
                                                    Name:    Madhu Philips
                                                    Title:   Vice President
                                                    Date:    March 15, 2006


<PAGE>



                                                                    Exhibit 31.2
                              COMPLIANCE STATEMENT

                  In connection with the preparation and delivery of the annual
report on Form 10-K of MS Structured Asset Corp. on behalf of SATURNS Trust No.
2001-4 for the fiscal year ending December 31, 2005, and the certifications
given by Madhu Philips with respect thereto, the undersigned hereby certifies
that she is a duly elected Vice President of LaSalle Bank National Association
and further certifies in her capacity as such as follows:


1.    LaSalle Bank National Association has prepared all distribution reports
with respect to each distribution date for SATURNS Trust No. 2001-4, and has
filed a copy of such reports on Form 8-K during the fiscal year as described on
Exhibit A hereto.

2.    I have reviewed all reports on Form 8-K containing distribution reports
filed in respect of periods included in the fiscal year covered by the annual
report of MS Structured Asset Corp. on behalf of SATURNS Trust No. 2001-4;

3.    I am familiar with the operations of LaSalle Bank National Association
with respect to the SATURNS program and SATURNS Trust No. 2001-4 and the
requirement imposed by the applicable trust agreement;

4.    Based on my knowledge, the information in the distribution reports, taken
as a whole, does not contain any untrue statement of a material fact or omit to
state a material fact necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading as of the
last day of the period covered by the annual report;

5.    Based on my knowledge, the information required to be provided under each
trust agreement, for inclusion in these reports, is included in these reports;

6.    Based on my knowledge, and except as disclosed in the reports, the trustee
has fulfilled its obligations, including any servicing obligations, under the
trust agreement.

7.    Based on my knowledge, and except as disclosed in the reports, there are
nomaterial legal proceedings with respect to any trust, involving the trust or
LaSalle Bank National Association as trustee.


                                                    By:     /s/ Barbara L. Marik
                                                       -------------------------
                                                    Name:   Barbara L. Marik
                                                    Title:  First Vice President
                                                    Date:   March 22, 2006


<PAGE>



                                                                       EXHIBIT A

<TABLE>
<CAPTION>
SATURNS Trust No.:     Closing Date     Payment Dates       Form 8-K Filing Dates (Not Trust
                                                          Agreement Filings in connection with
                                                                     Closing Date)

                                                                     For FY 2005
<S>                    <C>              <C>               <C>
2001-4                 6/4/01           March 1 and       March 4, 2005 and September 7, 2005
                                        September 1
</TABLE>