| Item 1. | |
| (a) | Name of issuer:
Calamos Strategic Total Return Fund |
| (b) | Address of issuer's principal executive offices:
2020 Calamos Court C/o Calamos Advisors LLC Naperville, IL, 60563 |
| Item 2. | |
| (a) | Name of person filing:
This statement is filed by: (i) Athene Annuity and Life Company ("AAIA"); (ii) Apollo Insurance Solutions Group LP ("AISG"); (iii) AISG GP Ltd. ("AISG GP"); (iv) Apollo Life Asset, L.P. ("Apollo Life"); (v) Apollo Life Asset GP, LLC ("Apollo Life GP"); (vi) Apollo Capital Management, L.P. ("Capital Management"); (vii) Apollo Capital Management GP, LLC ("Capital Management GP"); (viii) Apollo Management Holdings, L.P. ("Management Holdings"); and (ix) Apollo Management Holdings GP, LLC ("Management Holdings GP"). The foregoing are collectively referred to herein as the "Reporting Persons."
AAIA holds Series F Mandatory Redeemable Preferred Shares (the "MRPS") of the Issuer. AISG is the investment adviser of AAIA. AISG GP is the general partner of AISG. Apollo Life is the general partner of AISG GP, and Apollo Life GP is the general partner of Apollo Life. Capital Management is the sole member of Apollo Life GP. The general partner of Capital Management is Capital Management GP. Management Holdings is the sole member and manager of Capital Management GP, and Management Holdings GP is the general partner of Management Holdings. |
| (b) | Address or principal business office or, if none, residence:
The address of the principal office of AAIA is 7700 Mills Civic Parkway, West Des Moines, Iowa 50266. The address of the principal office of AISG is 2121 Rosecrans Ave., Ste 5300, El Segundo, California 90245. The address of the principal office of each of AISG GP and Apollo Life GP is c/o Walkers Corporate Limited, 190 Elgin Avenue, George Town, KY1-9008 Grand Cayman, Cayman Islands. The address of the principal office of each of Apollo Life, Capital Management, Capital Management GP, Management Holdings, and Management Holdings GP is 9 West 57th Street, 41st Floor, New York, NY 10019. |
| (c) | Citizenship:
AAIA Iowa
AISG Delaware
AISG GP Cayman Islands
Apollo Life Delaware
Apollo Life GP Cayman Islands
Capital Management Delaware
Capital Management GP Delaware
Management Holdings Delaware
Management Holdings GP Delaware |
| (d) | Title of class of securities:
Series F Mandatory Redeemable Preferred Shares |
| (e) | CUSIP No.:
128125*60 |
| Item 3. | If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a: |
| (a) |  Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
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| (b) | Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
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| (c) |  Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
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| (d) | Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
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| (e) | An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
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| (f) | An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
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| (g) | A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
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| (h) | A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
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| (i) | A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
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| (j) | A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
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| (k) | Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
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| Item 4. | Ownership |
| (a) | Amount beneficially owned:
Information in Rows 5 to 11 of the respective cover pages of the individual Reporting Persons are incorporated into this Item 4 by reference.
AISG, AISG GP, Apollo Life, Apollo Life GP, Capital Management, Capital Management GP, Management Holdings, and Management Holdings GP each disclaim beneficial ownership of all Common Stock included in this report, and the filing of this report shall not be construed as an admission that any such person or entity is the beneficial owner of any such securities for purposes of Section 13(d) or 13(g) of the Securities Exchange Act of 1934, as amended, or for any other purpose. |
| (b) | Percent of class:
Information in Rows 5 to 11 of the respective cover pages of the individual Reporting Persons are incorporated into this Item 4 by reference.
The Reporting Persons' aggregate percentage of beneficial ownership of the total amount of MRPS outstanding is based on 4,000,000 shares of the MRPS outstanding as of April 30, 2025, as reported by the Issuer in its certified shareholder report filed with the Securities and Exchange Commission on June 27, 2025. |
| (c) | Number of shares as to which the person has:
|
| | (i) Sole power to vote or to direct the vote:
0 for all Reporting Persons
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| | (ii) Shared power to vote or to direct the vote:
AAIA 1,920,000
AISG 1,920,000
AISG GP 1,920,000
Apollo Life 1,920,000
Apollo Life GP 1,920,000
Capital Management 1,920,000
Capital Management GP 1,920,000
Management Holdings 1,920,000
Management Holdings GP 1,920,000
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| | (iii) Sole power to dispose or to direct the disposition of:
0 for all Reporting Persons
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| | (iv) Shared power to dispose or to direct the disposition of:
AAIA 1,920,000
AISG 1,920,000
AISG GP 1,920,000
Apollo Life 1,920,000
Apollo Life GP 1,920,000
Capital Management 1,920,000
Capital Management GP 1,920,000
Management Holdings 1,920,000
Management Holdings GP 1,920,000
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| Item 5. | Ownership of 5 Percent or Less of a Class. |
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| Item 6. | Ownership of more than 5 Percent on Behalf of Another Person. |
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Not Applicable
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| Item 7. | Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person. |
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If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
See response to Item 2(a), which is incorporated by reference herein. |
| Item 8. | Identification and Classification of Members of the Group. |
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Not Applicable
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| Item 9. | Notice of Dissolution of Group. |
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Not Applicable
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