N-CEN: Filer Information

Filer CIK

0001275214

Filer CCC

********

Filer Investment Company Type

Form N-2 Filer (Closed-End Investment Company)

Is this a LIVE or TEST Filing?

LIVE

TEST

Is this an electronic copy of an official filing submitted in paper format?

Submission Contact Information

Name

Phone

E-Mail Address

Notification Information

Notify via Filing Website only?

N-CEN:Part A: General Information

Item A.1. Reporting period covered.

a. Report for period ending:

2025-10-31

b. Does this report cover a period of less than 12 months?

Yes

N-CEN:Part B: Information About the Registrant

Item B.1. Background information.

a. Full name of Registrant

CALAMOS STRATEGIC TOTAL RETURN FUND

b. Investment Company Act file number ( e.g., 811-)

811-21484

c. CIK

0001275214

d. LEI

54930048NQ2YBS3TXW78

Item B.2. Address and telephone number of Registrant.

a. Street 1

2020 CALAMOS COURT

Street 2

b. City

NAPERVILLE

c. State, if applicable

ILLINOIS

d. Foreign country, if applicable

UNITED STATES OF AMERICA

e. Zip code and zip code extension, or foreign postal code

60563

f. Telephone number (including country code if foreign)

630-245-7200

g. Public Website, if any

www.calamos.com

Item B.3. Location of books and records.

Instruction. Provide the requested information for each person maintaining physical possession of each account, book, or other document required to be maintained by section 31(a) of the Act (15 U.S.C. 80a-30(a)) and the rules under that section.

Location books Record: 1

a. Name of person (e.g., a custodian of records)

Calamos Advisors LLC

b. Street 1

2020 Calamos Court

Street 2

c. City

Naperville

d. State, if applicable

ILLINOIS

e. Foreign country, if applicable

UNITED STATES OF AMERICA

f. Zip code and zip code extension, or foreign postal code

60563

g. Telephone number (including country code if foreign)

630-245-7200

h. Briefly describe the books and records kept at this location:

All records in its capacity as investment adviser

Location books Record: 2

a. Name of person (e.g., a custodian of records)

Computershare Inc.

b. Street 1

150 Royall Street

Street 2

c. City

Canton

d. State, if applicable

MASSACHUSETTS

e. Foreign country, if applicable

UNITED STATES OF AMERICA

f. Zip code and zip code extension, or foreign postal code

02021

g. Telephone number (including country code if foreign)

866-226-8016

h. Briefly describe the books and records kept at this location:

All records in its capacity as transfer agent

Location books Record: 3

a. Name of person (e.g., a custodian of records)

State Street Bank and Trust Company

b. Street 1

1 Congress Street

Street 2

Suite 1

c. City

Boston

d. State, if applicable

MASSACHUSETTS

e. Foreign country, if applicable

UNITED STATES OF AMERICA

f. Zip code and zip code extension, or foreign postal code

02114

g. Telephone number (including country code if foreign)

617-786-3000

h. Briefly describe the books and records kept at this location:

Mutual fund accounting and records related to custody of fund assets.

Item B.4. Initial or final filings.

Instruction. Respond "yes" to Item B.4.b only if the Registrant has filed an application to deregister or will file an application to deregister before its next required filing on this form.

a. Is this the first filing on this form by the Registrant?

Yes

b. Is this the last filing on this form by the Registrant?

Yes

Item B.5. Family of investment companies.

Instruction. "Family of investment companies" means, except for insurance company separate accounts, any two or more registered investment companies that (i) share the same investment adviser or principal underwriter; and (ii) hold themselves out to investors as related companies for purposes of investment and investor services.In responding to this item, all Registrants in the family of investment companies should report the name of the family of investment companies identically.

Insurance company separate accounts that may not hold themselves out to investors as related companies (products) for purposes of investment and investor services should consider themselves part of the same family if the operational or accounting or control systems under which these entities function are substantially similar.

a. Is the Registrant part of a family of investment companies?

Yes

i. Full name of family of investment companies

Calamos Family of Funds

Item B.6. Organization.

Instruction. For Item B.6.a.i., the Registrant should include all Series that have been established by the Registrant and have shares outstanding (other than shares issued in connection with an initial investment to satisfy section 14(a) of the Act).

Indicate the classification of the Registrant by checking the applicable item below.

a. Open-end management investment company registered under the Act on Form N-1A
Checkbox checked

b. Closed-end management investment company registered under the Act on Form N-2
Checkbox not checked

c. Separate account offering variable annuity contracts which is registered under the Act as a management investment company on Form N-3
Checkbox not checked

d. Separate account offering variable annuity contracts which is registered under the Act as a unit investment trust on Form N-4
Checkbox not checked

e. Small business investment company registered under the Act on Form N-5
Checkbox not checked

f. Separate account offering variable insurance contracts which is registered under the Act as a unit investment trust on Form N-6
Checkbox not checked

g. Unit investment trust registered under the Act on Form N-8B-2

Item B.7. Securities Act registration.

Is the Registrant the issuer of a class of securities registered under the Securities Act of 1933 ("Securities Act")?

Yes

Item B.8. Directors.

Provide the information requested below about each person serving as director of the Registrant (management investment companies only):

Director Record: 1

a. Full Name

Christopher M. Toub

b. CRD number, if any

001741400

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-09237

File Number Record: 3

File Number Record:

811-21080

File Number Record: 4

File Number Record:

811-21319

File Number Record: 5

File Number Record:

811-21547

File Number Record: 6

File Number Record:

811-22047

File Number Record: 7

File Number Record:

811-22887

File Number Record: 8

File Number Record:

811-22949

File Number Record: 9

File Number Record:

811-23295

File Number Record: 10

File Number Record:

811-23815

File Number Record: 11

File Number Record:

811-23822

File Number Record: 12

File Number Record:

811-24034

File Number Record: 13

File Number Record:

811-24073

Director Record: 2

a. Full Name

Hugh P. Armstrong

b. CRD number, if any

N/A

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-09237

File Number Record: 3

File Number Record:

811-21080

File Number Record: 4

File Number Record:

811-21319

File Number Record: 5

File Number Record:

811-21547

File Number Record: 6

File Number Record:

811-22047

File Number Record: 7

File Number Record:

811-22887

File Number Record: 8

File Number Record:

811-22949

File Number Record: 9

File Number Record:

811-23295

File Number Record: 10

File Number Record:

811-23822

Director Record: 3

a. Full Name

Jeffrey S. Phlegar

b. CRD number, if any

N/A

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-09237

File Number Record: 3

File Number Record:

811-21080

File Number Record: 4

File Number Record:

811-21319

File Number Record: 5

File Number Record:

811-21547

File Number Record: 6

File Number Record:

811-22047

File Number Record: 7

File Number Record:

811-22887

File Number Record: 8

File Number Record:

811-22949

File Number Record: 9

File Number Record:

811-23295

File Number Record: 10

File Number Record:

811-23822

Director Record: 4

a. Full Name

John E. Neal

b. CRD number, if any

N/A

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-09237

File Number Record: 3

File Number Record:

811-21080

File Number Record: 4

File Number Record:

811-21319

File Number Record: 5

File Number Record:

811-21547

File Number Record: 6

File Number Record:

811-22047

File Number Record: 7

File Number Record:

811-22887

File Number Record: 8

File Number Record:

811-22949

File Number Record: 9

File Number Record:

811-23295

File Number Record: 10

File Number Record:

811-23815

File Number Record: 11

File Number Record:

811-23822

File Number Record: 12

File Number Record:

811-24034

File Number Record: 13

File Number Record:

811-24073

Director Record: 5

a. Full Name

John P. Calamos, Sr.

b. CRD number, if any

000038210

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-09237

File Number Record: 3

File Number Record:

811-21080

File Number Record: 4

File Number Record:

811-21319

File Number Record: 5

File Number Record:

811-21547

File Number Record: 6

File Number Record:

811-22047

File Number Record: 7

File Number Record:

811-22887

File Number Record: 8

File Number Record:

811-22949

File Number Record: 9

File Number Record:

811-23295

File Number Record: 10

File Number Record:

811-23822

Director Record: 6

a. Full Name

John S. Koudounis

b. CRD number, if any

001878118

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-09237

File Number Record: 3

File Number Record:

811-21080

File Number Record: 4

File Number Record:

811-21319

File Number Record: 5

File Number Record:

811-21547

File Number Record: 6

File Number Record:

811-22047

File Number Record: 7

File Number Record:

811-22887

File Number Record: 8

File Number Record:

811-22949

File Number Record: 9

File Number Record:

811-23295

File Number Record: 10

File Number Record:

811-23815

File Number Record: 11

File Number Record:

811-23822

File Number Record: 12

File Number Record:

811-24034

File Number Record: 13

File Number Record:

811-24073

Director Record: 7

a. Full Name

Karen L. Stuckey

b. CRD number, if any

N/A

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-09237

File Number Record: 3

File Number Record:

811-21080

File Number Record: 4

File Number Record:

811-21319

File Number Record: 5

File Number Record:

811-21547

File Number Record: 6

File Number Record:

811-22047

File Number Record: 7

File Number Record:

811-22887

File Number Record: 8

File Number Record:

811-22949

File Number Record: 9

File Number Record:

811-23295

File Number Record: 10

File Number Record:

811-23822

Director Record: 8

a. Full Name

Lloyd A. Wennlund

b. CRD number, if any

001512907

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-09237

File Number Record: 3

File Number Record:

811-21080

File Number Record: 4

File Number Record:

811-21319

File Number Record: 5

File Number Record:

811-21547

File Number Record: 6

File Number Record:

811-22047

File Number Record: 7

File Number Record:

811-22887

File Number Record: 8

File Number Record:

811-22949

File Number Record: 9

File Number Record:

811-23295

File Number Record: 10

File Number Record:

811-23556

File Number Record: 11

File Number Record:

811-23822

Director Record: 9

a. Full Name

Virginia G. Breen

b. CRD number, if any

N/A

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-06292

File Number Record: 3

File Number Record:

811-08764

File Number Record: 4

File Number Record:

811-08767

File Number Record: 5

File Number Record:

811-09237

File Number Record: 6

File Number Record:

811-21080

File Number Record: 7

File Number Record:

811-21195

File Number Record: 8

File Number Record:

811-21201

File Number Record: 9

File Number Record:

811-21319

File Number Record: 10

File Number Record:

811-21547

File Number Record: 11

File Number Record:

811-22047

File Number Record: 12

File Number Record:

811-22078

File Number Record: 13

File Number Record:

811-22500

File Number Record: 14

File Number Record:

811-22887

File Number Record: 15

File Number Record:

811-22949

File Number Record: 16

File Number Record:

811-23170

File Number Record: 17

File Number Record:

811-23171

File Number Record: 18

File Number Record:

811-23176

File Number Record: 19

File Number Record:

811-23245

File Number Record: 20

File Number Record:

811-23290

File Number Record: 21

File Number Record:

811-23291

File Number Record: 22

File Number Record:

811-23292

File Number Record: 23

File Number Record:

811-23295

File Number Record: 24

File Number Record:

811-23315

File Number Record: 25

File Number Record:

811-23365

File Number Record: 26

File Number Record:

811-23436

File Number Record: 27

File Number Record:

811-23441

File Number Record: 28

File Number Record:

811-23591

File Number Record: 29

File Number Record:

811-23647

File Number Record: 30

File Number Record:

811-23750

File Number Record: 31

File Number Record:

811-23755

File Number Record: 32

File Number Record:

811-23822

File Number Record: 33

File Number Record:

811-24037

Director Record: 10

a. Full Name

William R. Rybak

b. CRD number, if any

N/A

c. Is the person an "interested person" of the Registrant as that term is defined in section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19))?

Yes

d. Investment Company Act file number of any other registered investment company for which the person also serves as a director (e.g., 811-)

File Number Record: 1

File Number Record:

811-05443

File Number Record: 2

File Number Record:

811-08894

File Number Record: 3

File Number Record:

811-09237

File Number Record: 4

File Number Record:

811-10041

File Number Record: 5

File Number Record:

811-21080

File Number Record: 6

File Number Record:

811-21319

File Number Record: 7

File Number Record:

811-21547

File Number Record: 8

File Number Record:

811-22047

File Number Record: 9

File Number Record:

811-22887

File Number Record: 10

File Number Record:

811-22949

File Number Record: 11

File Number Record:

811-23295

File Number Record: 12

File Number Record:

811-23822

File Number Record: 13

File Number Record:

811-23889

File Number Record: 14

File Number Record:

811-23920

Item B.9. Chief compliance officer.

Provide the information requested below about each person serving as chief compliance officer of the Registrant for purposes of rule 38a-1 (17 CFR 270.38a- 1):

Chief compliance officer Record: 1

a. Full Name

Walter Kelly

b. CRD Number, if any

004729454

c. Street Address 1

215 N. Peoria

Street Address 2

d. City

Chicago

e. State, if applicable

ILLINOIS

f. Foreign country, if applicable

UNITED STATES OF AMERICA

g. Zip code and zip code extension, or foreign postal code

60607

h. Telephone number (including country code if foreign)

XXXXXX

i. Has the chief compliance officer changed since the last filing?

Yes

If the chief compliance officer is compensated or employed by any person other than the Registrant, or an affiliated person of the Registrant, for providing chief compliance officer services, provide:

CCO employer Record: 1

i. Name of the person

N/A

ii. Person's IRS Employer Identification Number

N/A

Item B.10. Matters for security holder vote.

Instruction. Registrants registered on Forms N-3, N-4 or N-6, should respond "yes" to this Item only if security holder votes were solicited on contract-level matters.

Were any matters submitted by the Registrant for its security holders' vote during the reporting period?

Yes

a. If yes, and to the extent the response relates only to certain series of the Registrant, indicate the series involved:

Security Matter Series info Record: 1

1. Series name

N/A

2. Series identification number

N/A

Item B.11. Legal proceeding.

Instruction. For purposes of this Item, the following proceedings should be described: (1) any bankruptcy, receivership or similar proceeding with respect to the Registrant or any of its significant subsidiaries; (2) any proceeding to which any director, officer or other affiliated person of the Registrant is a party adverse to the Registrant or any of its subsidiaries; and (3) any proceeding involving the revocation or suspension of the right of the Registrant to sell securities.

a. Have there been any material legal proceedings, other than routine litigation incidental to the business, to which the Registrant or any of its subsidiaries was a party or of which any of their property was the subject during the reporting period?

Yes

b. Has any proceeding previously reported been terminated?

Yes

Item B.12. Fidelity bond and insurance (management investment companies only).

a. Were any claims with respect to the Registrant filed under a fidelity bond (including, but not limited to, the fidelity insuring agreement of the bond) during the reporting period?

Yes

Item B.13. Directors and officers/errors and omissions insurance (management investment companies only).

a. Are the Registrant's officers or directors covered in their capacities as officers or directors under any directors and officers/errors and omissions insurance policy owned by the Registrant or anyone else?

Yes

i. If yes, were any claims filed under the policy during the reporting period with respect to the Registrant?

Yes

Item B.14. Provision of financial support.

Instruction. For purposes of this Item, a provision of financial support includes any (1) capital contribution, (2) purchase of a security from a Money Market Fund in reliance on rule 17a-9 under the Act (17 CFR 270.17a-9), (3) purchase of any defaulted or devalued security at fair value reasonably intended to increase or stabilize the value or liquidity of the Registrant's portfolio, (4) execution of letter of credit or letter of indemnity, (5) capital support agreement (whether or not the Registrant ultimately received support), (6) performance guarantee, or (7) other similar action reasonably intended to increase or stabilize the value or liquidity of the Registrant's portfolio. Provision of financial support does not include any (1) routine waiver of fees or reimbursement of Registrant's expenses, (2) routine inter-fund lending, (3) routine inter-fund purchases of Registrant's shares, or (4) action that would qualify as financial support as defined above, that the board of directors has otherwise determined not to be reasonably intended to increase or stabilize the value or liquidity of the Registrant's portfolio.

Did an affiliated person, promoter, or principal underwriter of the Registrant, or an affiliated person of such a person, provide any form of financial support to the Registrant during the reporting period?

Yes

Item B.15. Exemptive orders.

a. During the reporting period, did the Registrant rely on any orders from the Commission granting an exemption from one or more provisions of the Act, Securities Act or Exchange Act?

Yes

Release number Record: 1

i. If yes, provide below the release number for each order

IC-28483

Item B.16. Principal underwriters.

a. Provide the information requested below about each principal underwriter:

i. Full name

ii. SEC file number (e.g., 8-)

iii. CRD number

iv. Identifying number(s)

LEI

RSSD ID

v. State, if applicable

vi. Foreign country, if applicable

vii. Is the principal underwriter an affiliated person of the Registrant, or its investment adviser(s) or depositor?

Yes

b. Have any principal underwriters been hired or terminated during the reporting period?

Yes

Item B.17. Independent public accountant.

Provide the following information about each independent public accountant:

Public accountant Record: 1

a. Full Name

Deloitte & Touche LLP

b. PCAOB Number

c. Identifying number(s)

LEI

254900WYZPGQGKV3RF07

RSSD ID

d. State, if applicable

ILLINOIS

e. Foreign country, if applicable

UNITED STATES OF AMERICA

f. Has the independent public accountant changed since the last filing?

Yes

Item B.18. Report on internal control (management investment companies only).

Instruction. Small business investment companies are not required to respond to this item.

For the reporting period, did an independent public accountant's report on internal control note any material weaknesses?

Yes

Item B.19. Audit opinion.

For the reporting period, did an independent public accountant issue an opinion other than an unqualified opinion with respect to its audit of the Registrant's financial statements?

Yes

Item B.20. Change in valuation methods.

Instruction. Responses to this item need not include changes to valuation techniques used for individual securities (e.g., changing from market approach to income approach for a private equity security). In responding to Item B.20.c., provide the applicable "asset type" category specified in Item C.4.a. of Form N-PORT. In responding to Item B.20.d., provide a brief description of the type of investments involved. If the change in valuation methods applies only to certain sub-asset types included in the response to Item B.20.c., please provide the sub-asset types in the response to Item B.20.d. The responses to Item B.20.c. and Item B.20.d. should be identical only if the change in valuation methods applies to all assets within that category.

Have there been material changes in the method of valuation (e.g., change from use of bid price to mid price for fixed income securities or change in trigger threshold for use of fair value factors on international equity securities) of the Registrant's assets during the reporting period?

Yes

Item B.21. Change in accounting principles and practices.

Have there been any changes in accounting principles or practices, or any change in the method of applying any such accounting principles or practices, which will materially affect the financial statements filed or to be filed for the current year with the Commission and which has not been previously reported?

Yes

Item B.23. Rule 19a-1 notice (management investment companies only).

During the reporting period, did the Registrant pay any dividend or make any distribution in the nature of a dividend payment, required to be accompanied by a written statement pursuant to section 19(a) of the Act (15 U.S.C. 80a-19(a)) and rule 19a-1 thereunder (17 CFR 270.19a-1)?

Yes

Payment dividend series info Record: 1

a. If yes, and to the extent the response relates only to certain series of the Registrant, indicate the series involved:

i. Series name

N/A

ii. Series identification number

N/A

N-CEN:Part C: Additional Questions for Management Investment Companies

General Instruction.

Management investment companies that offer multiple series must complete Part C as to each series separately, even if some information is the same for two or more series. To begin this section or add an additional series(s), click on the bar labeled "Add a New Series" below.

Management Investment Record: 1

Item C.1. Background information.

a. Full Name of the Fund

CALAMOS STRATEGIC TOTAL RETURN FUND

b. Series identication number, if any

c. LEI

54930048NQ2YBS3TXW78

d. Is this the first filing on this form by the Fund?

Yes

Item C.2. Classes of open-end management investment companies.

a. How many Classes of shares of the Fund (if any) are authorized?

b. How many new Classes of shares of the Fund were added during the reporting period?

c. How many Classes of shares of the Fund were terminated during the reporting period?

d. For each Class with shares outstanding, provide the information requested below:

Item C.3. Type of fund.

Instructions. 1. "Fund of Funds" means a fund that acquires securities issued by any other investment company in excess of the amounts permitted under paragraph (A) of section 12(d)(1) of the Act (15 U.S.C. 80a-12(d)(1)(A)), but, for purposes of this Item, does not include a fund that acquires securities issued by another company solely in reliance on rule 12d1-1 under the Act (CFR 270.12d1-1). 2. "Index Fund" means an investment company, including an Exchange-Traded Fund, that seeks to track the performance of a specified index. 3. "Interval Fund" means a closed-end management investment company that makes periodic repurchases of its shares pursuant to rule 23c-3 under the Act (17 CFR 270.23c-3). 4. "Master-Feeder Fund" means a two-tiered arrangement in which one or more funds (each a feeder fund) holds shares of a single Fund (the master fund) in accordance with section 12(d)(1)(E) of the Act (15 U.S.C. 80a-12(d)(1)(E)) or pursuant to exemptive relief granted by the Commission. 5. "Target Date Fund" means an investment company that has an investment objective or strategy of providing varying degrees of long-term appreciation and capital preservation through a mix of equity and fixed income exposures that changes over time based on an investor's age, target retirement date, or life expectancy.

Indicate if the Fund is any one of the types listed below. Check all that apply.

a. Exchange-Traded Fund or Exchange-Traded Managed Fund or offers a Class that itself is an Exchange-Traded Fund or Exchange-Traded Managed Fund
i. Checkbox not checked

Exchange-Traded Fund
ii. Checkbox not checked

Exchange-Traded Managed Fund
b. Checkbox not checked

Index Fund

c. Checkbox not checked

Seeks to achieve performance results that are a multiple of a benchmark, the inverse of a benchmark, or a multiple of the inverse of a benchmark
d. Checkbox not checked

Interval Fund
e. Checkbox not checked

Fund of Funds
f. Checkbox not checked

Master-Feeder Fund
g. Checkbox not checked

Money Market Fund
h. Checkbox not checked

Target Date Fund
i. Checkbox not checked

Underlying fund to a variable annuity or variable life insurance contract
Checkbox checked

N/A

Item C.4. Diversification.

Does the Fund seek to operate as a “non-diversified company” as such term is defined in section 5(b)(2) of the Act (15 U.S.C. 80a- 5(b) (2))?

Yes

Item C.5. Investments in certain foreign corporations.

Instruction. "Controlled foreign corporation" has the meaning provided in section 957 of the Internal Revenue Code [26 U.S.C. 957].

a. Does the fund invest in a controlled foreign corporation for the purpose of investing in certain types of instruments such as, but not limited to, commodities?

Yes

Item C.6. Securities lending.

Instruction. For purposes of this Item, other adverse impacts would include, for example, (1) a loss to the Fund if collateral and indemnification were not sufficient to replace the loaned securities or their value, (2) the Fund's ineligibility to vote shares in a proxy, or (3) the Fund's ineligibility to receive a direct distribution from the issuer.

a. Is the Fund authorized to engage in securities lending transactions?

Yes

b. Did the Fund lend any of its securities during the reporting period?

Yes

i. If yes, during the reporting period, did any borrower fail to return the loaned securities by the contractual deadline with the result that:

1. The Fund (or its securities lending agent) liquidated collateral pledged to secure the loaned securities?

Yes

2. The Fund was otherwise adversely impacted?

Yes

c. Provide the information requested below about each securities lending agent, if any, retained by the Fund:

Securities Lending Record: 1

i. Full name of securities lending agent

State Street Bank and Trust Company

ii. Identifying number(s)

LEI

571474TGEMMWANRLN572

RSSD ID

iii. Is the securities lending agent an affiliated person, or an affiliated person of an affiliated person, of the Fund?

Yes

iv. Does the securities lending agent or any other entity indemnify the fund against borrower default on loans administered by this agent?

Yes

v. If the entity providing the indemnification is not the securities lending agent, provide the following information:

Idemnity Providers Record: 1

1. Name of person providing indemnification

N/A

2. Identifying number(s)

LEI

RSSD ID

vi. Did the Fund exercise its indemnification rights during the reporting period?

Yes

d. If a person providing cash collateral management services to the Fund in connection with the Fund's securities lending activities does not also serve as securities lending agent, provide the following information about each cash collateral manager:

i. Full name of cash collateral manager:

ii. Identifying number(s)

LEI

RSSD ID

iii. Is the cash collateral manager an affiliated person, or an affiliated person of an affiliated person, of a securities lending agent retained by the Fund?

Yes

iv. Is the cash collateral manager an affiliated person, or an affiliated person of an affiliated person, of the Fund?

Yes

e. Types of payments made to one or more securities lending agents and cash collateral managers (check all that apply):

i. Revenue sharing split
Checkbox not checked

ii. Non-revenue sharing split (other than administrative fee)
Checkbox not checked

iii. Administrative fee
Checkbox not checked

iv. Cash collateral reinvestment fee
Checkbox not checked

v. Indemnification fee
Checkbox checked

vi. Other

N/A

If other, describe:

Calamos makes interest payments in connection with the leverage facility it receives from its custodian. As part of the facility agreement, the custodian generates a portion of the funding through a securities lending arrangement where securities are lent versus cash collateral. The income generated by these securities loans is retained by the custodian. The Fund pays a lower borrowing cost to the custodian than it would without the securities lending activities.

f. Provide the monthly average of the value of portfolio securities on loan during the reporting period

578,411,466.21000000

g. Provide the net income from securities lending activities

N/A

Item C.7. Reliance on certain statutory exemption and rules.

Did the Fund rely on the following statutory exemption or any of the rules under the Act during the reporting period? (check all that apply)

a. Rule 10f-3 (17 CFR 270.10f-3)
Checkbox checked

b. Rule 12d1-1 (17 CFR 270.12d1-1)
Checkbox not checked

c. Rule 15a-4 (17 CFR 270.15a-4)
Checkbox not checked

d. Rule 17a-6 (17 CFR 270.17a-6)
Checkbox not checked

e. Rule 17a-7 (17 CFR 270.17a-7)
Checkbox not checked

f. Rule 17a-8 (17 CFR 270.17a-8)
Checkbox not checked

g. Rule 17e-1 (17 CFR 270.17e-1)
Checkbox not checked

h. Rule 22d-1 (17 CFR 270.22d-1)
Checkbox not checked

i. Rule 23c-1 (17 CFR 270.23c-1)
Checkbox checked

j. Rule 32a-4 (17 CFR 270.32a-4)
Checkbox not checked

k. Rule 6c-11 (17 CFR 270.6c-11)
Checkbox not checked

l. Rule 12d1-4 (17 CFR 270.12d1-4)
Checkbox not checked

m. Section 12(d)(1)(G) of the Act (15 USC 80a-12(d)(1)(G))
Checkbox checked

n. Rule 18f-4 (17 CFR 270.18f-4)

Is the Fund excepted from the rule 18f-4 (17 CFR 270.18f-4) program requirement and limit on fund leverage risk under rule 18f-4(c)(4) (17CFR 270.18f-4(c)(4))?

ii.

Is the Fund a leveraged/inverse fund that, under rule 18f-4(c)(5) (17 CFR 270.18f-4(c)(5)), is excepted from the requirement to comply with the limit on fund leverage risk described in rule 18f-4(c)(2) (17 CFR 270.18f-4(c)(2))?

iii.

Did the Fund enter into any reverse repurchase agreements or similar financing transactions under rule 18f-4(d)(i) (17 CFR 270.18f-4(d)(i))?

iv.

Did the Fund enter into any reverse repurchase agreements or similar financing transactions under rule 18f-4(d)(ii) (17 CFR 270.18f-4(d)(ii))?

Did the Fund enter into any unfunded commitment agreements under rule 18f-4(e) (17 CFR 270.18f-4(e))?

vi.

Did the Fund invest in a security on a when-issued or forward-settling basis, or with a non-standard settlement cycle, in reliance on rule 18f-4(f) (17 CFR 270.18f-4(f))?

N/A

Item C.8. Expense limitations.

Instruction. Provide information concerning any direct or indirect limitations, waivers or reductions, on the level of expenses incurred by the fund during the reporting period. A limitation, for example, may be applied indirectly (such as when an adviser agrees to accept a reduced fee pursuant to a voluntary fee waiver) or it may apply only for a temporary period such as for a new fund in its start-up phase.

a. Did the Fund have an expense limitation arrangement in place during the reporting period?

Yes

b. Were any expenses of the Fund reduced or waived pursuant to an expense limitation arrangement during the reporting period?

Yes

c. Are the fees waived subject to recoupment?

Yes

d. Were any expenses previously waived recouped during the period?

Yes

Item C.9. Investment advisers.

a. Provide the following information about each investment adviser (other than a sub-adviser) of the Fund:

Investment Advisers Record: 1

i. Full name

Calamos Advisors LLC

ii. SEC file number (e.g., 801-)

801-29688

iii.CRD number

000105758

iv. Identifying number(s)

LEI

549300B31HSTBIV6QG26

RSSD ID

v. State, if applicable

ILLINOIS

vi. Foreign country, if applicable

UNITED STATES OF AMERICA

vii. Was the investment adviser hired during the reporting period?

Yes

b. If an investment adviser (other than a sub-adviser) to the Fund was terminated during the reporting period, provide the following with respect to each investment adviser:

i. Full name

ii. SEC file number (e.g., 801-)

iii. CRD number

iv. Identifying number(s)

LEI

RSSD ID

v. State, if applicable

vi. Foreign country, if applicable

vii. Termination date

c. For each sub-adviser to the Fund, provide the information requested:

i. Full name

ii. SEC file number (e.g., 801-), if applicable

iii. CRD number

iv. Identifying number(s)

LEI

RSSD ID

v. State, if applicable

vi. Foreign country, if applicable

vii. Is the sub-adviser an affiliated person of the Fund's investment adviser(s)?

Yes

viii. Was the sub-adviser hired during the reporting period?

Yes

d. If a sub-adviser was terminated during the reporting period, provide the following with respect to such sub-adviser:

i. Full name

ii. SEC file number (e.g., 801-)

iii. CRD number

iv. Identifying number(s)

LEI

RSSD ID

v. State, if applicable

vi. Foreign country, if applicable

vii. Termination date

Item C.10. Transfer agents.

a. Provide the following information about each person providing transfer agency services to the Fund:

Transfer Agents Record: 1

i. Full name

Computershare Inc.

ii.SEC file number (e.g., 84- or 85-)

084-05925

iii. Identifying number(s)

LEI

254900Y7PP3ZED9AUY94

RSSD ID

iv. State, if applicable

MASSACHUSETTS

v. Foreign country, if applicable

UNITED STATES OF AMERICA

vi. Is the transfer agent an affiliated person of the Fund or its investment adviser(s)?

Yes

vii. Is the transfer agent a sub-transfer agent?

Yes

b. Has a transfer agent been hired or terminated during the reporting period?

Yes

Item C.11. Pricing services.

a. Provide the following information about each person that provided pricing services to the Fund during the reporting period:

Pricing Services Record: 1

i. Full name

Bloomberg L.P.

ii. Identifying number(s)

LEI

549300B56MD0ZC402L06

RSSD ID

Other identifying number

Description of other identifying number

iii. State, if applicable

NEW YORK

iv. Foreign country, if applicable

UNITED STATES OF AMERICA

v. Is the pricing service an affiliated person of the Fund or its investment adviser(s)?

Yes

Pricing Services Record: 2

i. Full name

ICE Data Services, Inc.

ii. Identifying number(s)

LEI

RSSD ID

Other identifying number

13-3668779

Description of other identifying number

Tax ID

iii. State, if applicable

GEORGIA

iv. Foreign country, if applicable

UNITED STATES OF AMERICA

v. Is the pricing service an affiliated person of the Fund or its investment adviser(s)?

Yes

Pricing Services Record: 3

i. Full name

London Stock Exchange Group PLC

ii. Identifying number(s)

LEI

213800QAUUUP6I445N30

RSSD ID

Other identifying number

Description of other identifying number

iii. State, if applicable

iv. Foreign country, if applicable

UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND

v. Is the pricing service an affiliated person of the Fund or its investment adviser(s)?

Yes

Pricing Services Record: 4

i. Full name

PricingDirect Inc.

ii. Identifying number(s)

LEI

549300WIC0TOJ7N7GD54

RSSD ID

Other identifying number

Description of other identifying number

iii. State, if applicable

NEW YORK

iv. Foreign country, if applicable

UNITED STATES OF AMERICA

v. Is the pricing service an affiliated person of the Fund or its investment adviser(s)?

Yes

Pricing Services Record: 5

i. Full name

S&P Global Inc.

ii. Identifying number(s)

LEI

Y6X4K52KMJMZE7I7MY94

RSSD ID

Other identifying number

Description of other identifying number

iii. State, if applicable

NEW YORK

iv. Foreign country, if applicable

UNITED STATES OF AMERICA

v. Is the pricing service an affiliated person of the Fund or its investment adviser(s)?

Yes

b. Was a pricing service hired or terminated during the reporting period?

Yes

Item C.12. Custodians.

a. Provide the following information about each person that provided custodial services to the Fund during the reporting period:

Custodians Record: 1

i. Full name

BANCO CITI MEXICO S.A. INSTITUCION DE BANCA MULTIPLE, GRUPO FINANCIERO CITI MEXICO

ii. Identifying number(s)

LEI

529900H31AYI6WA1J534

RSSD ID

iii. State, if applicable

iv. Foreign country, if applicable

MEXICO

v. Is the custodian an affiliated person of the Fund or its investment adviser(s)?

Yes

vi. Is the custodian a sub-custodian?

Yes

vii. With respect to the custodian, check below to indicate the type of custody:

1.Bank - section 17(f)(1) (15 U.S.C. 80a-17(f)(1))
Radio button not checked

2.Member national securities exchange - rule 17f-1 (17 CFR 270.17f-1)
Radio button not checked

3.Self - rule 17f-2 (17 CFR 270.17f-2)
Radio button not checked

4.Securities depository - rule 17f-4 (17 CFR 270.17f-4)
Radio button checked

5.Foreign custodian - rule 17f-5 (17 CFR 270.17f-5)
Radio button not checked

6.Futures commission merchants and commodity clearing organizations - rule 17f-6 (17 CFR 270.17f-6)
Radio button not checked

7.Foreign securities depository - rule 17f-7 (17 CFR 270.17f-7)
Radio button not checked

8.Insurance company sponsor - rule 26a-2 (17 CFR 270.26a-2)
Radio button not checked

9.Other

Custodians Record: 2

i. Full name

BNP Paribas (Athens, Attica, GR, Branch)

ii. Identifying number(s)

LEI

R0MUWSFPU8MPRO8K5P83

RSSD ID

iii. State, if applicable

iv. Foreign country, if applicable

GREECE

SEC Form N-CEN filed by Calamos Strategic Total Return