Harvey AI Expands to 185K SF at SL Green’s One Madison Avenue

Harvey AI Corporation, also known as Harvey, is quickly expanding at SL Green Realty’s One Madison Avenue.

The artificial intelligence platform designed to assist law firms doubled its space in the building to 185,326 square feet, according to the landlord. The expansion comes after Harvey signed its first deal for 92,663 square feet on the entire sixth floor of the property in October. SL Green announced the deal as part of what it’s touting as the highest first-quarter of leasing volume in its 28-year history.

Asking rent at One Madison was $120 per square foot in October when Harvey signed its initial 10-year lease for 92,663 square feet.

“One Madison is the perfect manifestation of our platform, meeting the market demand for beautifully designed, innovatively amenitized and expertly managed trophy office space,” Steven Durels, SL Green’s director of leasing and real property, said in a statement. “It’s no wonder the building has proven to be a magnet for leading financial and tech firms alike, and Harvey AI’s expansion is the ultimate endorsement of our future-forward product.”

JLL’s Joseph Messina and Todd Stracci represented Harvey in the expansion deal while a separate JLL team of Paul Glickman, Alex Chudnoff, Ben Bass and Diana Biasotti handled negotiations on behalf of SL Green.

JLL did not immediately respond to a request for comment.

So far, the first quarter of 2026 has seen 900,000 square feet of leasing across SL Green’s New York City portfolio, which could result in a weighted average leased occupancy of 98 percent by the end of the year, SL Green announced.

The 1.4 million-square-foot office building a block south of Madison Square Park has a tenant roster that includes Sigma Computing with 64,077 square feet and tech giant IBM with 362,092 square feet.

Mark Hallum can be reached at mhallum@commercialobserver.com.