HALO: Material agreement · New financial obligation · Unregistered securities sale

Item 1.01 Entry into a Material Definitive Agreement. Convertible Notes Indentures On September 22, 2026, Halozyme Therapeutics, Inc. (the “Company,” “we,” “us” or “our”) completed its previously announced sale of $1,500.0 million aggregate principal amount of 1.50% Convertible Senior Notes due 2033 (the “Convertible Notes”), including $200.0 million in aggregate principal amount of its Convertible Notes purchased pursuant to the exercise by the initial purchasers (the “Initial Purchasers”) of the Convertible Notes of the option (the “Convertible Notes Option”) to purchase additional Convertible Notes. The Convertible Notes were issued pursuant to an indenture, dated as of September 22, 2026, (the “Indenture”) between the Company and The Bank of New York Mellon Trust Company, N.A., as trustee (the “Trustee”). The Company offered and sold the Convertible Notes in reliance on the exemption from registration provided by Section 4(a)(2) of the Securities Act of 1933, as amended (the “Securities Act”). The Initial Purchasers offered and sold the Convertible Notes to “qualified institutional buyers” pursuant to the exemption from registration provided by Rule 144A under the Securities Act. The offer and sale of the Convertible Notes and the shares of common stock issuable upon conversion of the Convertible Notes have not been registered under the Securities Act, or the securities laws of any other jurisdiction, and the Convertible Notes and such shares may not be offered or sold absent registration or an applicable exemption from registration requirements, or in a transaction not subject to, such registration requirements. The Company received net proceeds from the offering of approximately $1,471.1 million after deducting the Initial Purchasers’ discounts and commissions and