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, 2006

                                      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
           office)                                         (Zip Code)

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

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

Title of Each Class                   Name of Each Exchange on Which Registered

SATURNS Cummins Engine Company             New York Stock Exchange
Debenture-Backed 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. As
of March 7, 2007, 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:

 Trust              Underlying Security Issuer or Guarantor               CIK

2001-4                           Cummins Inc.                         0000026712


<PAGE>


                                    PART I

ITEM 1.  BUSINESS

     Not Applicable

ITEM 1A. RISK FACTORS

     Not Applicable

ITEM 1B. UNRESOLVED STAFF COMMENTS

     None

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


<PAGE>


ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

     Not Applicable

ITEM 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

     Not Applicable

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

     None

ITEM 9A. CONTROLS AND PROCEDURES

     Not Applicable

ITEM 9B. OTHER INFORMATION

      None

                                   PART III

ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

     None

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


<PAGE>


                                   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:

<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 2006
<S>                    <C>                   <C>                            <C>
2001-4                 6/4/01                March 1 and September 1        March 6, 2006 and September 7, 2006
</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 28, 2007

                                                 MS STRUCTURED ASSET CORP.
                                                 (Registrant)



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


<PAGE>


                                                                    Exhibit 31.1
                          Rule 13a-14(d) 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 28, 2007


<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, 2006, 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 no material 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 27, 2007


<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 2006
<S>                    <C>                   <C>                            <C>
2001-4                 6/4/01                March 1 and September 1        March 6, 2006 and September 7, 2006
</TABLE>