================================================================================ UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13D (Rule 13d-101) UNDER THE SECURITIES EXCHANGE ACT OF 1934 (AMENDMENT NO. ) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(a) Calamos Global Total Return Fund (NAME OF ISSUER) Series A Mandatory Redeemable Preferred Shares Series B Mandatory Redeemable Preferred Shares Series C Mandatory Redeemable Preferred Shares (TITLE OF CLASS OF SECURITIES) 128118*24 128118*32 128118*40 (CUSIP NUMBER) Steve Katz Donald Griffith Barings LLC Massachusetts Mutual Life Insurance Company 1500 Main Street, PO Box 15189 1295 State Street Springfield, MA 01115-5190 Springfield, Massachusetts 01111 (413) 226-1000 (800) 767-1000 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) September 6, 2017 (DATE OF EVENT WHICH REQUIRES FILING OF THIS STATEMENT) If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box [ ]. Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent. (Continued on following pages) ================================================================================ =================== ================= CUSIP No. 128118*24, 128118*32, 128118*40 13D PAGE 2 OF 8 PAGES =================== ================= ================================================================================ 1 NAMES OF REPORTING PERSONS: I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Massachusetts Mutual Life Insurance Company 04-1590850 ----- -------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) [_] (b) [_] ----- -------------------------------------------------------------------------- 3 SEC USE ONLY ----- -------------------------------------------------------------------------- 4 SOURCE OF FUNDS WC ----- -------------------------------------------------------------------------- 5 CHECK BOX IF THE DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) Not Applicable ----- -------------------------------------------------------------------------- 6 CITIZENSHIP OR PLACE OF ORGANIZATION Massachusetts -------------------------------------------------------------------------------- 7 SOLE VOTING POWER 0 NUMBER OF ----- ------------------------------------------------ SHARES 8 SHARED VOTING POWER BENEFICIALLY OWNED BY 480,000(1) EACH ----- ------------------------------------------------ REPORTING 9 SOLE DISPOSITIVE POWER PERSON WITH 0 ----- ------------------------------------------------ 10 SHARED DISPOSITIVE POWER 480,000(1) -------------------------------------------------------------------------------- 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 480,000(1) ----- -------------------------------------------------------------------------- 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES [ ] Not Applicable ----- -------------------------------------------------------------------------- 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11 100%(2) ----- -------------------------------------------------------------------------- 14 TYPE OF REPORTING PERSON CO, IC (1) Massachusetts Mutual Life Insurance Company ("MassMutual"), a Massachusetts corporation, is the direct beneficial owner of 480,000 Mandatory Redeemable Preferred Shares which are held in one or more advisory accounts. Barings LLC ("Barings"), a Delaware limited liability company and wholly-owned indirect subsidiary of MassMutual, acts as investment adviser to these advisory accounts, and as such may also be deemed to be the beneficial owner of these shares. (2) The referenced securities are preferred equity securities which the Reporting Persons are informed, represent, in the aggregate, 100% of the preferred equity securities of the Issuer. ================================================================================ =================== ================= CUSIP No. 128118*24, 128118*32, 128118*40 13D PAGE 3 OF 8 PAGES =================== ================= ================================================================================ 1 NAMES OF REPORTING PERSONS: I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Barings LLC 04-1054788 ----- -------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) [_] (b) [_] ----- -------------------------------------------------------------------------- 3 SEC USE ONLY ----- -------------------------------------------------------------------------- 4 SOURCE OF FUNDS WC ----- -------------------------------------------------------------------------- 5 CHECK BOX IF THE DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) Not Applicable ----- -------------------------------------------------------------------------- 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware -------------------------------------------------------------------------------- 7 SOLE VOTING POWER 0 NUMBER OF ----- ------------------------------------------------ SHARES 8 SHARED VOTING POWER BENEFICIALLY OWNED BY 480,000(1) EACH ----- ------------------------------------------------ REPORTING 9 SOLE DISPOSITIVE POWER PERSON WITH 0 ----- ------------------------------------------------ 10 SHARED DISPOSITIVE POWER 480,000(1) -------------------------------------------------------------------------------- 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 480,000(1) ----- -------------------------------------------------------------------------- 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES [ ] Not Applicable ----- -------------------------------------------------------------------------- 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11 100%(2) ----- -------------------------------------------------------------------------- 14 TYPE OF REPORTING PERSON IA (1) Barings, in its capacity as investment adviser, may be deemed to be the beneficial owner of 480,000 Mandatory Redeemable Preferred Shares, which are held in certain advisory accounts owned (directly or indirectly) or controlled by MassMutual. (2) The referenced securities are preferred equity securities which the Reporting Persons are informed, represent, in the aggregate, 100% of the preferred equity securities of the Issuer. ================================================================================ =================== ================= CUSIP No. 128118*24, 128118*32, 128118*40 13D PAGE 4 OF 8 PAGES =================== ================= Item 1. Security and Issuer: This statement relates to the Calamos Global Total Return Fund Series A, B and C Mandatory Redeemable Preferred Shares. The Issuer's principal offices are located at 2020 Calamos Court, Naperville, IL 60563. Item 2. Identity and Background: (a) This statement is filed by the entities listed below, all of whom together are referred to herein as the "Reporting Persons". (i) Massachusetts Mutual Life Insurance Company ("MassMutual") (ii)Barings LLC ("Barings") (b) MassMutual's principal office is located at 1295 State Street, Springfield, MA, 01111. The principal office for Barings is located at 300 South Tryon Street, Suite 2500, Charlotte, NC, 28202. (c) The principal business of MassMutual is that of a diversified financial services organization providing financial products and services that include mutual funds, money management, trust services, retirement planning products, life insurance, annuities, disability income insurance, and long-term care insurance. The officers and directors of MassMutual, who are all citizens of the United States, are as follows: Officers: Roger Crandall, Chairman, President and Chief Executive Officer Susan Cicco, Chief Human Resources Office Timothy Corbett, Chief Investment Officer Michael Fanning, Head of MassMutual U.S. Pia Flanagan, Corporate Secretary and Chief of Staff Brad Hoffman, Chief Risk Officer Michael O'Connor, General Counsel Mark Roellig, Chief Technology & Administrative Officer Gareth Ross, Chief Digital and Customer Experience Officer Elizabeth Ward, Chief Financial Officer and Chief Actuary Subsidiary Leadership Eddie Ahmed, Chairman and Chief Executive Officer, MassMutual International Tom Finke, Chairman and Chief Executive Officer, Barings LLC Art Steinmetz, Chairman, President and Chief Executive Officer, OppenheimerFunds Board of Directors: Roger W. Crandall Karen Bechtel Mark T. Bertolini Kathleen A. Corbet James H. DeGraffenreidt, Jr. Robert A. Essner Jeffrey M. Leiden, M.D., Ph.D. Cathy E. Minehan Marc F. Racicot Laura J. Sen William T. Spitz H. Todd Stitzer The principal business of Barings is that of an entrepreneurial capital management firm focused on creating innovative investment strategies and solutions for sophisticated investors. The officers and managers of Barings, who are all citizens of the United States, are as follows: Officers: Thomas M. Finke, Chairman and Chief Executive Officer Paul J. Thompson, Chief Financial Officer, Chief Operating Officer and Managing Director Susan A. Moore, Chief Administrative Officer and Managing Director Christopher A. DeFrancis, Chief Compliance Officer, Deputy Counsel and Managing Director Shelden M. Francis, Chief Legal Officer, Secretary and Managing Director Managers: Thomas M. Finke - Chairman William F. Glavin Jr. Roger W. Crandall Elizabeth A. Ward M. Timothy Corbett (d - e) During the last five years, none of the Reporting Persons nor any of the persons named above has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or was a party to a civil proceeding of judicial or administrative body of competent jurisdiction as a result of which any such person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws. (f) MassMutual is a Massachusetts corporation. Barings is a Delaware limited liability company. =================== ================= CUSIP No. 128118*24, 128118*32, 128118*40 13D PAGE 5 OF 8 PAGES =================== ================= Item 3 Source and Amount of Funds or Other Consideration: On September 6, 2017, MassMutual, through one or more advisory accounts for which Barings serves as investment adviser, acquired the Mandatory Redeemable Preferred Shares in the ordinary course of business using funds that came directly or indirectly from the working capital of MassMutual. Item 4 Purpose of Transaction: All of the Mandatory Redeemable Preferred Shares reported herein were acquired for investment purposes. The Reporting Persons do not at the present time have any plans or proposals which would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D. However, the Reporting Persons retain the right to modify plans with respect to the transactions described in this Schedule 13D, to vote, acquire or dispose of securities of the Issuer and to formulate plans and proposals which could result in the occurrence of any such events, subject to applicable laws and regulations. Item 5 Interest in Securities of the Issuer: (a) As of September 6, 2017, MassMutual and Barings may each be deemed to have beneficially own the 480,000 Mandatory Redeemable Preferred Shares referenced herein. The Reporting Persons are informed, such securities represent, in the aggregate, 100% of the preferred equity securities of the Issuer. (b) MassMutual has shared power with Barings to vote and dispose of the 480,000 of Mandatory Redeemable Preferred Shares for which it is deemed the beneficial owner. Barings has shared power with MassMutual to vote and dispose of the 480,000 of Mandatory Redeemable Preferred Shares for which it is deemed the beneficial owner. (c) Not Applicable. (d) Not Applicable. (e) Not Applicable. =================== ================= CUSIP No. 128118*24, 128118*32, 128118*40 13D PAGE 6 OF 8 PAGES =================== ================= Item 6 Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer: Not Applicable. Item 7 Material to be Filed as Exhibits: Not Applicable. =================== ================= CUSIP No. 128118*24, 128118*32, 128118*40 13D PAGE 7 OF 8 PAGES =================== ================= 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. Dated: September 14, 2017 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY By: --------------------------- Name: Donald Griffith Title: Vice President BARINGS LLC By: --------------------------- Name: Ann Malloy Title: Director =================== ================= CUSIP No. 128118*24, 128118*32, 128118*40 13D PAGE 8 OF 8 PAGES =================== ================= AGREEMENT REGARDING THE JOINT FILING OF SCHEDULE 13D The undersigned hereby agree that the statement on Schedule 13D to which this Agreement is annexed as Exhibit 1 is filed on behalf of each of them in accordance with the provisions of Rule 13d-1(k) under the Securities Act of 1934, as amended. Dated: September 14, 2017 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY By: --------------------------- Name: Donald Griffith Title: Vice President BARINGS LLC By: --------------------------- Name: Ann Malloy Title: Director