Apollo entities (CSQ) report 15.2% stake in Calamos Series F preferred

Rhea-AI Filing Summary

Athene Annuity and Life Company and affiliated Apollo entities report beneficial ownership of 608,000 Series F Mandatory Redeemable Preferred Shares of Calamos Strategic Total Return Fund. This represents 15.2% of the Series F MRPS, based on 4,000,000 shares outstanding as of April 30, 2026.

All reporting entities list 0 shares with sole voting or dispositive power and 608,000 shares with shared voting and shared dispositive power. Several Apollo-related entities file on a joint basis and, other than Athene as holder, broadly disclaim beneficial ownership of the securities beyond what may be imputed under Section 13(d) or 13(g).

Key Figures

Shares beneficially owned: 608,000 shares Percent of Series F class: 15.2% Series F shares outstanding: 4,000,000 shares +2 more

5 metrics

Shares beneficially owned 608,000 shares Series F Mandatory Redeemable Preferred Shares reported by the group

Percent of Series F class 15.2% Ownership percentage of Series F MRPS based on outstanding shares

Series F shares outstanding 4,000,000 shares Series F MRPS outstanding as of April 30, 2026

Sole voting power 0 shares Sole voting power reported by each reporting person

Shared voting power 608,000 shares Shared voting power over Series F MRPS for all reporting persons

Key Terms

Series F Mandatory Redeemable Preferred Shares, beneficial ownership, shared voting power, dispositive power, +1 more

5 terms

Series F Mandatory Redeemable Preferred Shares financial

"Title of class of securities: Series F Mandatory Redeemable Preferred Shares"

beneficial ownership financial

"Amount beneficially owned: Information in Row 9 of the respective cover pages"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

shared voting power financial

"Shared power to vote or to direct the vote: 608,000 for all Reporting Persons"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

dispositive power financial

"Shared power to dispose or to direct the disposition of: 608,000 for all Reporting Persons"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

parent holding company financial

"Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company"

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Available on EDGAR 07/28/2026 - 04:05 PM Accepted by SEC EDGAR 07/28/2026 - 04:05 PM Learn about SEC filing dates

FAQ

How many Calamos Strategic Total Return Fund (CSQ) Series F MRPS do the Apollo-related reporting persons own?

The reporting persons disclose beneficial ownership of 608,000 Series F Mandatory Redeemable Preferred Shares of Calamos Strategic Total Return Fund. Athene Annuity and Life Company is the direct holder, with related Apollo entities reporting due to their advisory and control relationships.

What percentage of the Series F Mandatory Redeemable Preferred Shares of CSQ is owned by the reporting group?

The filing states the group holds 15.2% of the Series F MRPS. This percentage is calculated using 4,000,000 Series F shares outstanding as of April 30, 2026, as reported by Calamos in its certified shareholder report.

Which entities are included as reporting persons in this Schedule 13G/A for CSQ?

Reporting persons include Athene Annuity and Life Company and several Apollo-affiliated entities, such as Apollo Insurance Solutions Group LP, AISG GP Ltd., Apollo Life Asset, L.P., Apollo Life Asset GP, LLC, Apollo Capital Management, L.P., Apollo Capital Management GP, LLC, Apollo Management Holdings, L.P., and Apollo Management Holdings GP, LLC.

What voting and dispositive powers over CSQ’s Series F MRPS do the reporting persons claim?

Each reporting person reports 0 shares with sole voting and sole dispositive power and 608,000 shares with shared voting and shared dispositive power. This indicates decisions over these shares are exercised jointly among the reporting group rather than individually.

Do the Apollo-affiliated reporting persons claim full beneficial ownership of CSQ’s Series F MRPS?

The filing states that AISG, AISG GP, Apollo Life, Apollo Life GP, Capital Management, Capital Management GP, Management Holdings, and Management Holdings GP each disclaim beneficial ownership of the securities. Their reporting arises from their roles in the ownership and advisory chain, not direct holding of the shares.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 10)

Calamos Strategic Total Return Fund

(Name of Issuer)

Series F Mandatory Redeemable Preferred Shares

(Title of Class of Securities)

012812560

(CUSIP Number)

06/18/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

Apollo Management Holdings GP, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

Athene Annuity and Life Company

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

IOWA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

IC

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

Apollo Insurance Solutions Group LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

AISG GP Ltd.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

Apollo Life Asset L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

Apollo Life Asset GP, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

Apollo Capital Management, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

Apollo Capital Management GP, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 012812560

1

Names of Reporting Persons

Apollo Management Holdings, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 608,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 608,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

608,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

15.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

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 "Series F MRPS") of the Issuer. AISG is the investment adviser of AAIA. AISG GP is the general partner of AISG. Apollo Life is the sole shareholder 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 AISG 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, Apollo Life GP, 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 Delaware 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.: 012812560
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);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(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);
(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:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: Information in Row 9 of the respective cover pages of the individual Reporting Persons is incorporated into this Item 4(a) 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 Row 11 of the respective cover pages of the individual Reporting Persons is incorporated into this Item 4(b) by reference. The Reporting Persons' aggregate percentage of beneficial ownership of the total amount of Series F MRPS outstanding is based on 4,000,000 shares of the Series F MRPS outstanding as of April 30, 2026, as reported by the Issuer in its certified shareholder report filed with the Securities and Exchange Commission on July 2, 2026.
(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
	(ii) Shared power to vote or to direct the vote: 608,000 for all Reporting Persons
	(iii) Sole power to dispose or to direct the disposition of: 0 for all Reporting Persons
	(iv) Shared power to dispose or to direct the disposition of: 608,000 for all Reporting Persons
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	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.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Apollo Management Holdings GP, LLC

Signature:	/s/ William B. Kuesel
Name/Title:	William B. Kuesel, Vice President
Date:	07/28/2026

Athene Annuity and Life Company

Signature:	Apollo Insurance Solutions Group LP
Name/Title:	Investment Adviser
Date:	07/28/2026

Signature:	AISG GP Ltd.
Name/Title:	General Partner
Date:	07/28/2026

Signature:	/s/ Angelo Lombardo
Name/Title:	Angelo Lombardo, Authorized Signatory
Date:	07/28/2026

Apollo Insurance Solutions Group LP

Signature:	AISG GP Ltd.
Name/Title:	General Partner
Date:	07/28/2026

Signature:	/s/ Angelo Lombardo
Name/Title:	Angelo Lombardo, Authorized Signatory
Date:	07/28/2026

AISG GP Ltd.

Signature:	/s/ Angelo Lombardo
Name/Title:	Angelo Lombardo, Authorized Signatory
Date:	07/28/2026

Apollo Life Asset L.P.

Signature:	Apollo Life Asset GP, LLC
Name/Title:	General Partner
Date:	07/28/2026

Signature:	Apollo Capital Management, L.P.
Name/Title:	Managing Member
Date:	07/28/2026

Signature:	Apollo Capital Management GP, LLC
Name/Title:	General Partner
Date:	07/28/2026

Signature:	/s/ William Kuesel
Name/Title:	William B. Kuesel, Vice President
Date:	07/28/2026

Apollo Life Asset GP, LLC

Signature:	Apollo Capital Management, L.P.
Name/Title:	Managing Member
Date:	07/28/2026

Signature:	Apollo Capital Management GP, LLC
Name/Title:	General Partner
Date:	07/28/2026

Signature:	/s/ William B. Kuesel
Name/Title:	William B. Kuesel, Vice President
Date:	07/28/2026

Apollo Capital Management, L.P.

Signature:	Apollo Capital Management GP, LLC
Name/Title:	General Partner
Date:	07/28/2026

Signature:	/s/ William B. Kuesel
Name/Title:	William B. Kuesel, Vice President
Date:	07/28/2026

Apollo Capital Management GP, LLC

Signature:	/s/ William B. Kuesel
Name/Title:	William B. Kuesel, Vice President
Date:	07/28/2026

Apollo Management Holdings, L.P.

Signature:	Apollo Management Holdings GP, LLC
Name/Title:	General Partner
Date:	07/28/2026

Signature:	/s/ William B. Kuesel
Name/Title:	William B. Kuesel, Vice President
Date:	07/28/2026