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Harvey AI Expansion Brings One Madison Avenue to Full Occupancy as SL Green Targets Record Q1 Leasing

Amenities-driven adaptive reuse is drawing long-term tech commitments in Midtown South.

Overview

  • Harvey AI doubled its footprint to 185,326 square feet at One Madison Avenue, taking the final available office space and bringing the building to 100% leased.
  • SL Green reported 832,135 square feet of leasing across 44 deals in the first 65 days of 2026 and now projects more than 900,000 square feet by quarter end, a first‑quarter record for the company.
  • The One Madison redevelopment combines a restored nine‑story podium with a new 550,000‑square‑foot tower designed by KPF overlooking Madison Square Park.
  • Tenants at the 1.4 million‑square‑foot property include IBM, Franklin Templeton, Palo Alto Networks, FanDuel Group, Sigma Computing and Coinbase, with amenities such as 100% fresh‑air HVAC, a Rockwell Group rooftop event space, Daniel Boulud’s La Tête d’Or, The Commons lounge and Chelsea Piers Fitness.
  • JLL brokered the Harvey transactions for both sides, and separate leasing also brought nearby 11 Madison Avenue to full occupancy with AI firm Clay signing for 163,000 square feet.