Arrowhead Pharmaceuticals Inc美股招股说明书(2026-01-07版)

% Convertible Senior Notes due 2032 We are offering $500,000,000 aggregate principal amount of our% convertible senior notes due 2032. In addition, we have granted the underwriters an option,which is exercisable within 30 days after the date of this prospectus supplement, to purchase up to an additional $75,000,000 aggregate principal amount of notessolely to cover over-allotments.MATURITY; INTEREST We will pay interest on the notes at an annual rate of%, payable semi-annually in arrears on January15 and July15 of each year, beginning on July15, 2026. Thenotes will mature on January15, 2032, unless earlier converted or redeemed or repurchased by us.CONVERSION Noteholders may convert their notes at their option only in the following circumstances: (1)during any calendar quarter commencing after the calendar quarter ending on March31, 2026, if the last reported sale price per share of our common stock exceeds 130% of the conversion price for each of at least 20 trading days during the30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter; (2)during the five consecutive business daysimmediately after any 10 consecutive trading day period (such 10 consecutive trading day period, the “measurement period”) in which the trading price per $1,000principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of our commonstock on such trading day and the conversion rate on such trading day; (3)upon the occurrence of certain corporate events or distributions on our common stock, asdescribed in this prospectus supplement; (4)if we call such notes for redemption; and (5)at any time from, and including, October15, 2031 until the close of businesson the second scheduled trading day immediately before the maturity date. We will settle conversions by paying or delivering, as applicable, cash, shares of ourcommon stock or a combination of cash and shares of our common stock, at our election, based on the applicable conversion rate(s). The initial conversion rate isshares per $1,000 principal amount of notes, which represents an initial conversion price of approximately $per share, and is subject to adjustment as described in this prospectus supplement. If a “make-whole fundamental change” (as defined in this prospectus supplement) occurs, then we will in certaincircumstances increase the conversion rate for a specified period of time.REDEMPTION AND REPURCHASE The notes will be redeemable, in whole or in part (subject to certain limitations described in this prospectus supplement), at our option at any time, and from time totime, on or after January16, 2029 and on or before the 30th scheduled trading day immediately before the maturity date, at a cash redemption price equal to theprincipal amount of the notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date, but only if the last reported sale price pershare of our common stock exceeds 130% of the conversion price on (1)each of at least 20 trading days, whether or not consecutive, during the 30 consecutive tradingdays ending on, and including, the trading day immediately before the date we send the related redemption notice; and (2)the trading day immediately before the datewe send such notice. In addition, calling any note for redemption will constitute a make-whole fundamental change with respect to that note, in which case theconversion rate applicable to the conversion of that note will be increased in certain circumstances if it is converted after it is called for redemption.If a “fundamental change” (as defined in this prospectus supplement) occurs, then, except as described in this prospectus supplement, noteholders may require us torepurchase their notes at a cash repurchase price equal to the principal amount of the notes to be repurchased, plus accrued and unpaid interest, if any.RANKING The notes will be our senior, unsecured obligations and will be equal in right of payment with our existing and future senior, unsecured indebtedness, senior in right ofpayment to our existing and future indebtedness that is expressly subordinated to the notes and effectively subordinated to our existing and future securedindebtedness, to the extent of the value of the collateral securing that indebtedness. The notes will be structurally subordinated to all existing and future indebtednessand other liabilities, including trade payables, and (to the extent we are not a holder thereof) preferred equity, if any, of our subsidiaries.CONCURRENT COMMON STOCK OFFERING Concurrently with this offering, we are offering, pursuant to a separate prospectus supplement $200,000,000 of our common stock, plus up to an additional$30,000,000 of our common stock that the underwriters of the concurrent common stock offering have the option to purchase from us. The completion of this offeringis not con