The Mark tower, now F5 Tower, is under construction now. (The Mark Photo)

Updated below with financial terms of the lease.

F5 Networks has leased all of the office space in an eye-catching skyscraper under construction in downtown Seattle, previously known as The Mark, the company confirmed today.

With the lease, the building will be called F5 Tower. The network infrastructure and security technology company will move all of its Seattle employees into the building in 2019, from its current location on the Seattle waterfront. The lease includes 516,000 square feet of office space, the biggest lease so far in 2017 in the city. In addition to the office space, the 44-story tower will also include an SLS Hotel.

F5 has leased all of the office space in the 44-story skyscraper that will now be called F5 Tower, the angular building to the left of the 76-story Columbia Center in this rendering. (Image: The Mark)

It’s a high-profile new home for a company that operates behind-the-scenes of the online world. Puget Sound Business Journal first reported on the lease.

An F5 spokesman said the company has 1,375 employees in Seattle and adds about 100 per year. F5 also has an outpost in Bellevue. Those employees won’t be consolidating into the new building and will stay put on the Eastside.

The networking technology company is currently headquartered in the Interbay area, north of downtown Seattle is cramped for space, and had been looking for a new home for more than a year. It added space in its current building, but that wasn’t enough.

F5 will not only have a new headquarters, but back in January at added a new CEO, Francois Locoh-Donou. He started last month.

Update, 2:20 p.m.: In a filing with the Securities and Exchange Commission this afternoon, F5 reported that it has leased the space for a total of 14.5 years, starting on April 1, 2019, or 10 months after the building is substantially completed, for a total cost of $359.5 million over the term of the lease.

Like what you're reading? Subscribe to GeekWire's free newsletters to catch every headline

Job Listings on GeekWork

Find more jobs on GeekWork. Employers, post a job here.