Bloomberg LP, the media company founded in 1981 by future three-term Mayor Michael Bloomberg, just gave Midtown’s sleepiest office corridor a badly needed shot of adrenaline.

In a surprise to commercial market-watchers, Bloomberg signed a nearly 1 million square-foot lease extension and expansion at SL Green’s 919 Third Ave. between East 55th and 56th streets. The 47 story tower is known as the “P.J. Clarke’s building” for the two-story, 1884 saloon structure on the corner that’s regarded as part of the property.

Bloomberg extended its existing 749,035 square-foot lease for 11 years starting in March 2029. At the same time, it signed for an additional 175,841 square feet on part of the 34th floor and the entire floors on 35 and 41-44.

Bloomberg signed a nearly 1 million square-foot lease extension and expansion at SL Green’s 919 Third Ave. between East 55th and 56th streets.

Talks for large office transactions with marquee-name companies usually make their way into the media long before the deals are completed — but not a word leaked out this time.

Bloomberg, which has steadily grown at 919 Third since it first moved into the tower in 2015, plainly doesn’t listen to claims that “work from home” means smaller corporate footprints. Earlier this year, the company extended its lease at its 731 Lexington Ave. headquarters until 2040.

While Third Avenue suffers Midtown’s highest vacancy rate of over 20% — a drag on the whole market — 919 Third’s 1.5 million square feet are 92.1% leased. Other major office tenants include financial legal specialists Schulte Roth & Zabel, and the law firm Mintz, Levin, Cohn, Ferris, Glovsky and Popeo.

A commercial broker who wasn’t involved in the deal but didn’t want to be named commented, “Maybe all the ‘Dead Avenue’  jokes were premature.”

The 47 story tower is known as the “P.J. Clarke’s building” for the two-story, 1884 saloon structure on the corner that’s regarded as part of the property. Julie Scarlet Stapen

The Bloomberg deal marks another advance for SL Green, which has signed nearly 2.8 million square feet of Manhattan offices this year. The  city’s largest commercial landlord expects to complete more than 3.3 million square feet of deals by the end of 2024.

SLG is also closing in on 1.1 million square feet in potential new Manhattan leases, including term sheets and deals under negotiation.

Steven Durels, executive VP and director of leasing for SL Green, said, “Overall leasing velocity continues to increase as tenants prioritize their preference for well-located, upgraded and amenitized buildings.”

Bloomberg has steadily grown at 919 Third since it first moved into the tower in 2015. Founder and former NYC Mayor Michael Bloomberg, above. AP

Bloomberg was represented at 919 Third by CBRE’s Howard Fiddle, Chris Mansfield, Zach Weil and Ryan Luck. SL Green was represented by Robert Alexander, Ryan Alexander, Emily Chabrier, Taylor Callahan, Alex D’Amario and Nicole Marshall of CBRE.

Read More