https://qz.com/1216164/the-size-of-silicon-valleys-bay-area-real-estate-empires-charted/

Alphabet, Apple, and Facebook have tens of thousands of employees in the Bay Area, all of whom need space to do their jobs. As a result, the tech giants command millions of square feet in the region.

Alphabet alone owns or leases 19.9 million square feet in the Bay Area, nearly four times as much as the area’s largest commercial real estate firm, Hudson Pacific Properties, according to the San Francisco Chronicle and San Francisco Business Times.