Growing fintech firm Clear Street likes its digs at Silverstein’s Four World Trade Center so much, it’s extending its lease by 10 years and adding an entire floor.

Clear Street added 44,716 feet to expand its headquarters to 88,000 square feet. The company first moved to the tower in 2021 in a sublease from MediaMath and two years later, converted to a direct lease for the whole 45th floor. It will now expand into the entire 46th floor.

Clear Street COO Jon Daplyn said the tower’s “innovative design, spectacular views and proximity to transit have enabled our team to grow and thrive. Having additional space is essential to our future growth.”

The 2.3 million square-foot tower is 97% leased. Other large tenants include Spotify, Zurich American Insurance, Duolingo, SNY, and Rippling.

Silverstein was repped in-house by Keith A. Cody and Gordon L. Hough. Clear Street was repped by Norman Bobrow & Company’s Josh Berger.