Halozyme Therapeutics plans to offer $1.05 billion of convertible senior notes due 2033, subject to market conditions and other factors, and expects to give initial purchasers a 13-day option to buy up to an additional $150 million. The senior, unsecured securities would mature on October 1, 2033, unless earlier redeemed, repurchased or converted. They would be sold only to persons reasonably believed to be qualified institutional buyers under Rule 144A of the Securities Act of 1933. Interest, the initial conversion rate and other terms will be set at pricing. Halozyme expects to use part of the proceeds for capped call transactions, privately negotiated repurchases of its 0.25% convertible senior notes due 2027 and 1.00% convertible senior notes due 2028, and general corporate purposes. Capped calls are derivatives intended to limit dilution or offset certain cash payments when the stock price exceeds the notes' conversion price, although protection would not extend above the capped-call cap price. The company warned that note repurchases and related hedging by existing holders, initial purchasers or option counterparties could affect Halozyme's stock and note prices, conversion conditions and the value or number of shares delivered upon conversion. The proposed securities and any shares issuable on conversion have not been registered and would be offered only under an applicable exemption or through a private offering memorandum. Halozyme said the offering remains subject to uncertainty, including whether it will proceed and what its final terms and use of proceeds will be.