[6-K] SUN LIFE FINANCIAL INC Current Report (Foreign Issuer)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16

under the Securities Exchange Act of

1934

For the month of November, 2025 Commission File Number:001-15014

SUN LIFE FINANCIAL INC.

(the “Company”)

(Translation of registrant’s name into English)

1 York Street, 31st Floor, Toronto, Ontario M5J 0B6

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F            Form 40-F    X

Exhibit

99.1    Press Release dated November 5, 2025 – Sun Life Reports Third Quarter 2025 Results

SIGNATURE

Pursuant to the requirement of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Sun Life Financial Inc.

                        (Registrant)

Date: November 5, 2025                By    /s/ “Kevin Armitage”            

                            Kevin Armitage

    AVP & Managing Counsel, Corporate Legal

Exhibit 99.1