UNITED
STATESSECURITIES AND EXCHANGE COMMISSIONWASHINGTON, D.C. 20549








FORM 10-KFOR ANNUAL AND TRANSITION REPORTSPURSUANT TO SECTIONS 13 OR 15(d) OF THESECURITIES EXCHANGE ACT OF 1934



(Mark
One)



| | ☒ | ANNUAL
                                         REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
| | - | -----------------------------------------------------------------------------------------------------------------------------



For
the fiscal year ended December 31, 2017



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 Number of issuing entity: 001-33605Central Index Key Number of issuing entity: 0001405198





| | STRATS Trust for AMBAC Financial Group, Inc. Securities,
Series 2007-1 | 
| | ---------------------------------------------------------------------- | 
| | (Exact name of issuing entity as specified in its charter)             | 



Commission
File Number of depositor and sponsor: 001-31818
Central Index Key Number of depositor and sponsor: 0001140396





| | Synthetic
    Fixed-Income Securities, Inc.                       | 
| | ----------------------------------------------------------------- | 
| | (Exact name of depositor and sponsor as specified in its charter) | 



|New
    York                                                       | 20-7474289                              
|------------------------------------------------------------------ | ----------------------------------------
|(State
    or other jurisdiction of incorporation or organization) | (I.R.S.
    Employer Identification No.)
|                                                                   |                                         
|301
    South College Street, Charlotte, North Carolina            | 28288                                   
|(Address
    of principal executive offices)                       | (Zip
    Code)                          
|                                                                   |                                         

Registrant’s
telephone number, including area code: (212) 214-6277



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



|Title
    of each class                |  | Name
    of Registered exchange on which registered
|-------------------------------------- |  | ---------------------------------------------------
|                                       |  |                                                    
|STRATS
    Certificates, Series 2007-1 |  | New
    York Stock Exchange                        



Securities
registered pursuant to Section 12(g) of the Act: None.



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



Indicate
by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.
Yes ☐   No ☒



Indicate
by check mark whether the 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 ☒   No ☐



Indicate
by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive
Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the
preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).
Yes ☒   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.
Not applicable.



Indicate by check mark whether the registrant
is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth
company. See the definitions of “large accelerated filer,” “accelerated filer,” “non-accelerated
filer,” “smaller reporting company, “and “emerging growth company” in Rule 12b-2 of the Exchange Act.



|Large accelerated filer ☐ | Accelerated filer ☐         |                          
|------------------------- | --------------------------- | -------------------------
|                          |                             |                          
|Non-accelerated filer ☒   | Smaller Reporting Company ☐ | Emerging Growth Company ☐



If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐



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



State
the aggregate market value of the voting and non-voting common equity held by non-affiliates computed by reference to the price
at which the common equity was last sold, or the average bid and asked price of such common equity, as of the last business day
of the registrant’s most recently completed second fiscal quarter:



The
registrant has no voting stock or class of common stock that is held by non-affiliates.
















DOCUMENTS
INCORPORATED BY REFERENCE



None.



Introductory
Note



Synthetic
Fixed-Income Securities, Inc. (the “Depositor”) is the Depositor in respect of the STRATS Trust for AMBAC Financial
Group, Inc. Securities, Series 2007-1 (the “Trust”), a common law trust formed pursuant to the Base Trust Agreement,
dated as of September 8, 2006, between the Depositor and U.S. Bank Trust National Association, as trustee (the “Trustee”),
as supplemented by the STRATS Certificates Series Supplement 2007-1 (the “Series Supplement”) dated as of July 16,
2007 in respect of the Trust. The Trust’s assets consist solely of DISCS issued by Ambac Financial Group Inc. The Certificates
do not represent obligations of or interests in the Depositor or the Trustee.











Pursuant
to staff administrative positions established in Corporate Asset Backed Corporation (available August 9, 1995), the Trust 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 the Trust are filed after each distribution date on Form 10-D in lieu of
reports on Form 10-Q. AMBAC Financial Group, Inc., the issuer of the underlying securities, is subject to the information
reporting requirements of the Securities Exchange Act of 1934 (the “Exchange Act”). For information on AMBAC Financial
Group, Inc. please see its periodic and current reports filed with the Securities and Exchange Commission (the “Commission”)
under its Exchange Act file number, 001-10777. The Commission maintains a site on the World Wide Web at “http://www.sec.gov”
at which users can view and download copies of reports, proxy and information statements and other information filed electronically
through the Electronic Data Gathering, Analysis and Retrieval system, or “EDGAR.” Periodic and current reports and
other information required to be filed pursuant to the Exchange Act by AMBAC Financial Group, Inc. may be accessed on this site.
You can request copies of these documents, upon payment of a duplicating fee, by writing to the SEC. The public may read and copy
any materials filed with the Commission at the Commission’s Public Reference Room at 100 F Street, NE, Washington, DC 20549.
The public may obtain information on the operation of the Public Reference Room by calling the Commission at 1-800-SEC-0330.  Please
call the SEC at 1-800-SEC-0330 for further information on the operation of the SEC’s public reference rooms. Neither Synthetic
Fixed-Income Securities, Inc. nor the Trustee has participated in the preparation of such reporting documents, or made any due
diligence investigation with respect to the information provided therein. Neither Synthetic Fixed-Income Securities, Inc. nor
the Trustee has verified the accuracy or completeness of such documents or reports. There can be no assurance that events affecting
the issuer of the underlying securities or the underlying securities themselves have not occurred or have not yet been publicly
disclosed which would affect the accuracy or completeness of the publicly available documents described above.



2







PART
I



The
following Items have been omitted in accordance with General Instruction J to Form 10-K:



Item
1. Business.



Item
1A. Risk Factors.



Item
2. Properties.



Item
3. Legal Proceedings.



Item
1B. Unresolved Staff Comments.



Not
Applicable.



Item
4. Mine Safety Disclosures.



Not
Applicable.



PART
II



The
following Items have been omitted in accordance with General Instruction J to Form 10-K:



Item
5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities.



Item
6. Selected Financial Data.



Item
7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.



Item
7A. Quantitative and Qualitative Disclosures About Market Risk.



Item
8. Financial Statements and Supplementary Data.



Item
9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure.



Item
9A. Controls and Procedures.



Item
9B. Other Information.



None.



PART
III



The
following Items have been omitted in accordance with General Instruction J to Form 10-K:



Item
10. Directors, Executive Officers and Corporate Governance.



Item
11. Executive Compensation.



Item
12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.



Item
13. Certain Relationships and Related Transactions, and Director Independence.



Item
14. Principal Accounting Fees and Services.



3







SUBSTITUTE
INFORMATION PROVIDED IN ACCORDANCE WITH GENERAL INSTRUCTION J(2) TO FORM 10-K.



|Item
    1112(b) of Regulation AB.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Significant
    Obligors of Pool Assets (Financial Information).                                                                                                                                                                                            
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|The
                                         primary asset of the issuing entity is the underlying securities, $37,500,000 of 6.15%
                                         DISCS due February 15, 2037 issued by AMBAC Financial Group, Inc. The issuer of the underlying
                                         securities, therefore, may be considered a significant obligor. The issuer of the underlying
                                         securities is subject to the information reporting requirements of the Securities Exchange
                                         Act of 1934 (the “Exchange Act”). For information on the issuer of the underlying
                                         securities please see its periodic and current reports filed with the Securities and
                                         Exchange Commission (the “Commission”) under its Exchange Act file number,
                                         001-10777.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|Item
    1114(b)(2) of Regulation AB.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | Credit
                                         Enhancement and Other Support, Except for Certain Derivatives
        
        Instruments
        (Information Regarding Significant Enhancement
        
        Providers
        Financial Information).
|Based
    on the standards set forth in Item 1114(b)(2) of Regulation AB, no information is required in response to this Item.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Item
                                         1115(b) of Regulation AB.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | Certain
    Derivatives Instruments (Financial Information).                                                                                                                                                                                                
|Based
    on the standards set forth in Item 1115(b) of Regulation AB, no information is required in response to this Item.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Item
                                         1117 of Regulation AB.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | Legal
    Proceedings.                                                                                                                                                                                                                                      
|There
    are no legal proceedings pending, or any proceedings known to be contemplated, by governmental authorities against the depositor,
    the Trustee or the issuing entity, or any property thereof, that is material to the holders of the Certificates.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|Item
    1119 of Regulation AB.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Affiliations
                                         and Certain Relationships and Related Transactions.                                                                                                                                                   
|Based
    on the standards set forth in Item 1119 of Regulation AB, no information is required in response to this Item.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|Item
    1122 of Regulation AB.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Compliance
                                         with Applicable Servicing Criteria.                                                                                                                                                                     
|U.S.
                                         Bank Trust National Association has been identified by the registrant as a party participating
                                         in the servicing function with respect to the pool assets held by STRATS Trust for AMBAC
                                         Financial Group, Inc. Securities, Series 2007-1. U.S. Bank Trust National Association
                                         has completed a report on an assessment of compliance with the servicing criteria applicable
                                         (the “Report on Assessment”) as of February 28, 2018 and for a period beginning
                                         January 1, 2017 through and including December 31, 2017, which Report on Assessment is
                                         attached as an exhibit to this Form 10-K. In addition, U.S. Bank Trust National Association
                                         has provided an attestation report (the “Attestation Report”) by a registered
                                         independent public accounting firm regarding its related Report on Assessment. The Attestation
                                         Report is attached as an exhibit to this Form 10-K. Neither the Report on Assessment
                                         or the related Attestation Report has identified any material instances of noncompliance
                                         with the servicing criteria described in the Report on Assessment as being applicable
                                         to U.S. Bank Trust National Association.
|Item
    1123 of Regulation AB.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Servicer
                                         Compliance Statement.                                                                                                                                                                                     
|U.S.
    Bank Trust National Association has provided a statement of compliance (the “Compliance Statement”) for the period
    from and including January 1, 2017 through and including December 31, 2017, which has been signed by an authorized officer
    of U.S. Bank Trust National Association. The Compliance Statement of U.S. Bank Trust National Association is attached as an
    exhibit to this Form 10-K.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        

4







PART IV



Item
15. Exhibits, Financial Statement Schedules.



(a)          The
following documents have been filed as part of this report.



| | 1. | None.
| | -- | -----



| | 2. | None.
| | -- | -----



| | 3. | Exhibits:
| | -- | ---------



31.1
– Certification by Director of the Registrant pursuant to 15 U.S.C. Section 7241, as adopted pursuant to Section 302
of the Sarbanes-Oxley Act of 2002.



33.1
– Report on Assessment of Compliance with Servicing Criteria for U.S. Bank Trust National Association for the period from
and including January 1, 2017 through and including December 31, 2017.



34.1
– Attestation Report of Ernst & Young LLP on Assessment of Compliance with Servicing Criteria relating to U.S. Bank
Trust National Association.
35.1 – Servicer Compliance Statement of U.S. Bank Trust National Association for the period from and including January 1,
2017 through and including December 31, 2017.



(b)          See
Item 15(a) above.



(c)          Not
Applicable.





5







SIGNATURE



Pursuant
to the requirements of Section 13 or 15(d) 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.



| |                                                                        |                          | 
| | ---------------------------------------------------------------------- | ------------------------ | 
| | Synthetic Fixed-Income Securities,
    Inc.,                          
| | as Depositor for the Trust                                            
| |                                                                        |                         
| | By:                                                                    | /s/
    Barbara Garafalo
| | Name:                                                                  | Barbara Garafalo        
| | Title:                                                                 | Vice President          
| |                                                                        |                         
| | (senior officer in charge of the
    securitizations of the depositor)



Dated:
March 30, 2018



6







EXHIBIT
INDEX



|Exhibit
    
Number in this 
Form 10-K | Description
    of Exhibits                                                                                                                                                                   
|-------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|31.1                                   | Certification by Director of the Registrant pursuant to 15 U.S.C. Section 7241, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                         
|33.1                                   | Report on Assessment of Compliance with Servicing Criteria for U.S. Bank Trust National Association for the period from and including January 1, 2017 through and including December 31, 2017.
|34.1                                   | Attestation Report of Ernst & Young LLP on Assessment of Compliance with Servicing Criteria relating to U.S. Bank Trust National Association.                                                 
|35.1                                   | Servicer Compliance Statement of U.S. Bank Trust National Association for the period from and including January 1, 2017 through and including December 31, 2017.                              



7