Exhibit 99.1 Phathom Pharmaceuticals Reports Second Quarter 2026 Financial Results and Provides Business Update FLORHAM PARK, N.J., July 30, 2026 — Phathom Pharmaceuticals, Inc. (Nasdaq: PHAT), a biopharmaceutical company focused on commercializing and developing novel treatments for gastrointestinal (GI) diseases, today reported financial results for the second quarter ended June 30, 2026, and provided a business update. "The second quarter marked an important milestone for Phathom as we delivered strong q ...