Pfizer Inc.

Item 8.01 Other Events. On November 21, 2025, Pfizer Inc. (the “Company”) completed a public offering of $500,000,000 aggregate principal amount of Floating Rate Notes due 2027 (the “Floating Rate Notes”), $1,000,000,000 aggregate principal amount of 3.875% Notes due 2027 (the “2027 Notes”), $1,000,000,000 aggregate principal amount of 4.200% Notes due 2030 (the “2030 Notes”), $1,250,000,000 aggregate principal amount of 4.500% Notes due 2032 (the “2032 Notes”), $1,250,000,000 aggregate principal amount of 4.875% Notes due 2035 (the “2035 Notes”), $500,000,000 aggregate principal amount of 5.600% Notes due 2055 (the “2055 Notes”) and $500,000,000 aggregate principal amount of 5.700% Notes due 2065 (the “2065 Notes” and, together with the Floating Rate Notes, the 2027 Notes, the 2030 Notes, the 2032 Notes, the 2035 Notes and the 2055 Notes, the “Notes”). The offering of the Notes was made pursuant to the shelf registration statement on Form S-3 (Registration No. 333-277323) of the Company, Pfizer Investment Enterprises Pte. Ltd. and Pfizer Netherlands International Finance B.V., originally filed with the Securities and Exchange Commission (the “Commission”) on February 23, 2024, as amended by the Post-Effective Amendment No. 1 thereto, filed with the Commission on May 13, 2025. The Notes were issued pursuant to an indenture (the “Base Indenture”), dated as of September 7, 2018, between the Company and The Bank of New York Mellon, as trustee (the “Trustee”), as supplemented by the sixth supplemental indenture (the “Sixth Supplemental Indenture” and, the Base Indenture as supplemented by the Sixth Supplemental Indenture, the “Indenture”), dated as of November 21, 2025, between the Company and the Trustee. The Sixth Supplemental Indenture is filed herewith as Exhibit 4.2 to this Current Report on Form 8-K and is incorporated herein by reference. Each of the form of Floating Rate Notes, the form of 2027 Notes, the form of 2030 Notes, the form of 2032 Notes, the form of 2035 Notes, the form of 2055 Notes and the form of 2065 Notes are filed herewith as Exhibit 4.3, Exhibit 4.4, Exhibit 4.5, Exhibit 4.6, Exhibit 4.7, Exhibit 4.8 and Exhibit 4.9 to this Current Report on Form 8-K, respectively, and are incorporated herein by reference. In connection with the offering of the Notes, the Company entered into an underwriting agreement (the “Underwriting Agreement”) and related pricing agreement (the “Pricing Agreement”), each dated November 18, 2025, with Citigroup Global Markets Inc., Deutsche Bank Securities Inc., J.P. Morgan Securities LLC and Mizuho Securities USA LLC, as representatives of the several underwriters listed on Schedule I to the Pricing Agreement. The Underwriting Agreement and the Pricing Agreement are filed herewith as Exhibit 1.1 and Exhibit 1.2 to this Current Report on Form 8-K, respectively, and are incorporated herein by reference. In addition, in connection with the offering of the Notes, the Company is filing a legal opinion regarding the validity of the Notes, which is filed herewith as Exhibit 5.1 to this Current Report on Form 8-K.