Day One Biopharmaceuticals Inc.

# Signal Note: Deerfield Management Initiates $34.7M Position in DAWN Deerfield's entry suggests confidence in Day One's pipeline, likely centered onetzrahyastat (TETZ), a first-in-class pyruvate dehydrogenase complex activator in Phase 2 for Leigh syndrome—a rare mitochondrial disorder with no approved treatments and significant unmet need. The $34.7M stake (substantial for a 3.7M share position) positions Deerfield to benefit from Phase 2 readout timing, expected within the next 12-18 months, which represents the key near-term catalyst for valuation re-rating.