On August 2, 2022, before market hours, Phathom issued a press release entitled “Phathom Pharmaceuticals Reports Second Quarter 2022 Financial Results and Provides Business Updates” which announced that “we detected trace levels of a nitrosamine in vonoprazan drug product in our post-approval testing as we prepared for commercial launch.” Further, the press release announced that “[t]he Company is working with the FDA and plans to obtain approval of and implement an additional test method, specification, including a proposed acceptable intake limit, and additional controls to address this impurity prior to releasing our first vonoprazan-based products to the market.” Finally, the Company announced that “[t]hese additional activities will result in a delay of the planned VOQUEZNA DUAL PAK and VOQUEZNA TRIPLE PAK product launches.”

On this news, Phathom’s stock price fell $2.61 per share, or 28%, to close at $6.46 per share on August 2, 2022.