Fred Alger is returning downtown.

The firm that lost 35 people on 9/11 has leased 50,040 square feet on the top three floors of 100 Pearl St. by Water Street — two of which are being newly built as a glass-enclosed penthouse with sprawling terraces overlooking the East River.

Fred Alger Management Chief Executive Dan Chung, son-in-law of the late founder, says “ Taking this new, beautiful space at 100 Pearl St., in part, commemorates those we lost during the 9/11 attacks and serves as an ongoing commitment to our team and our clients who have grown with us over the last 20 years.”

Fred Alger is at 360 Park Ave. So. and is expected to make its emotional move downtown in the fourth quarter of 2021.

The firm will then have a three-story headquarters consisting of the 27th floor of 37,115 square feet, plus the new, 7,425 square-foot 28th floor and 5,500 square-foot 29th floor with extra-high ceilings and 15,000 square feet of terraces.

The ownership of GFP Real Estate and Northwind Group are also undertaking a $250 million renovation of the entire 360,000-square-foot building designed by S9 Architecture.

Scott Galin and Darell Handler of Handler Real Estate Organization represented Fred Alger in the long-term lease, with an asking rent in the high $70s per square foot.

The building owners were represented by the Newmark Knight Frank team of Hal Stein, Ben Shapiro, Andrew Peretz, Dan Appel and Travis Wilson.

Today, Feb. 26, so we never forget, is the 27th anniversary of the first bombing in 1993 that killed six people.