MOUNTAIN VIEW — A tech titan has struck a deal to sell a big office campus in Mountain View, part of the company’s ongoing efforts to unload 10 buildings in Silicon Valley, according to a regulatory filing.

NortonLifeLock, formerly Symantec, has agreed to sell its main office complex in Silicon Valley for $358 million in cash, a filing with the Securities and Exchange Commission shows.

TMG Partners, a veteran Bay Area real estate developer and investor, intends to buy the five-building campus, which has addresses of 350 through 380 Ellis St. in Mountain View, according to the SEC documents that were filed by NortonLifeLock.

“The sale agreement provides that the sale of the Ellis Street property will close on June 30, 2021,” the SEC filing stated.

Arizona-based NortonLifeLock has been attempting to sell 10 buildings in Mountain View, including the five that are due to be sold by the end of this month, according to a sales brochure circulated in January 2020 by Cushman & Wakefield, a commercial real estate firm.

The first group of the 10 buildings was bought from NortonLIfeLock roughly two months ago.

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In April 2021, an alliance of Bay Area developer Steelwave and New York City-based real estate investor Angelo Gordon & Co. paid NortonLifeLock $100.5 million for two buildings on Whisman Road in Mountain View.

Still unsold: a complex at 455, 487, and 501 E. Middlefield Road, which contains older office and research buildings, as well as a data center. These three buildings total 128,000 square feet.

In the latest deal for the five buildings, TMG Partners agreed to lease back to NortonLIfeLock one of the buildings. The SEC filing didn’t specify the address other than to refer to the structure as “Building C.”

The lease is slated to last for seven years, although provisions were made for an early termination of the lease, the SEC filing showed.