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

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

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| New York                                                       |   | 20-7097869                           |
|----------------------------------------------------------------|--------|--------------------------------------|
| (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)                           |

| Title of each class                | Name of Registered exchange on which registered |
|------------------------------------|-------------------------------------------------|
|                               |                                            |
| STRATS Certificates, Series 2006-4 | New York Stock Exchange (“NYSE”)    |

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| Large accelerated filer  ☐ | Accelerated filer ☐ | Non- accelerated filer   ☒ | Smaller reporting company ☐ |
|---------------------------------------|---------------------------|--------------------------------------------|-----------------------------------|

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| Item 1112(b) of Regulation AB. | Significant Obligors of Pool Assets (Financial Information). |
|--------------------------------|--------------------------------------------------------------|
| Item 1114(b)(2) of Regulation AB. | Credit Enhancement and Other Support, Except for Certain Derivatives Instruments (Information Regarding Significant Enhancement Providers Financial Information). |
|-----------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Item 1115(b) of Regulation AB. | Certain Derivatives Instruments (Financial Information). |
|--------------------------------|----------------------------------------------------------|
| Item 1117 of Regulation AB. | Legal Proceedings. |
|-----------------------------|--------------------|
| Item 1119 of Regulation AB. | Affiliations and Certain Relationships and Related Transactions. |
|-----------------------------|------------------------------------------------------------------|
| Item 1122 of Regulation AB. | Compliance with Applicable Servicing Criteria |
|-----------------------------|-----------------------------------------------|

| Item 1123 of Regulation AB. | Servicer Compliance Statement. |
|-----------------------------|--------------------------------|

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

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

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

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

|  | (b) | See Item 15(a) above. |
|--|-----|-----------------------|

|  | (c) | Not Applicable. |
|--|-----|-----------------|

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|   | 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, 2016 |                                                               |   |   |

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| 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, 2015 through and including December 31, 2015. |
| 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, 2015 through and including December 31, 2015.                               |

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