SAN FRANCISCO—The Obvious Corp., led by Twitter founder Evan Williams, has leased three floors at the Phelan Building at 760 Market Street from Thor Equities.

Thor Equities CEO Joseph Sitt said Obvious signed an eight-year lease for about 75,000 square feet. The technology firm recently launched a new publishing platform called Medium.

"We need the right space from which to grow the Medium team and position Obvious to focus on bringing our new ideas to life," said Williams in a statement. "We're excited to get three custom floors on Market Street, in the heart of downtown. Being surrounded by like-minded peers in a creative space also serves as an inspiration."

Sitt said his firm has renovated and repositioned the property, also known as the Flatiron Building, which includes tenants Voxer and Appirio. "San Francisco real estate is white-hot right now, as digital entrepreneurs flock into the creative, urban city center from Silicon Valley," said Sitt in the statement.

Jenny Haeg with Custom Spaces Inc. represented Obvious in this deal.