What Day One Biopharmaceuticals, Inc. told the SEC could break it.

Day One's OJEMDA sales flow through a highly concentrated channel — two individual (unnamed) customers (its specialty pharmacy and specialty distributor) were 97.6% of total net product revenue in 2025 (66.7% and 30.9%); loss of either would sharply cut revenue.

“for the year ended December 31, 2025, two individual customers accounted for 97.6% of our total net product revenue, with these individual customers representing 66.7% and 30.9% of total net product revenue.”

Day One relies on a limited number of suppliers — some sole-source and some based in China — for raw materials/API to make OJEMDA and its candidates; complex materials are hard to substitute and China-based supply is exposed to disruption, sanctions and policy shifts.

“We rely on a limited number of suppliers, some of whom are our sole source for certain materials, and some of whom are based in foreign jurisdictions.”

With China-based manufacturers and imported API/intermediates, Day One is exposed to US tariffs on Chinese imports and on pharmaceutical products, which could raise its API/input costs and compress margins.

“The Company is sensitive to increased U.S. tariffs and other trade restrictions, including tariffs specifically on imports from China and tariffs on imports of pharmaceutical products from other jurisdictions. If such tariffs are expanded in scope, increased, or become permanent, the Company could experience higher costs on imported raw materials and product intermediates, which may compress margins.”