LinkedIn, setting the stage for a dramatic expansion in Sunnyvale, has bought two large sites and has leased a big new office building, moves that defy gloomy prognostications of a Silicon Valley tech exodus.

The tech titan paid $122.8 million for two research and office buildings with addresses of 810, 820 and 870 W. Maude Ave. in Sunnyvale, documents filed on Dec. 3 with the Santa Clara County Recorder’s Office show.

Separately, LinkedIn has leased a modern office building at 684 W. Maude Ave. in Sunnyvale that totals 194,600 square feet and is and across the street from the two sites that were bought by the employment-oriented social network.

The LinkedIn transactions in Sunnyvale were arranged through commercial real estate firms Colliers, Newmark and JLL, according to property experts familiar with the deals. The transactions all involved an existing building and future development sites in a Sunnyvale project called Catalyst.

Newmark brokers Mike Saign, Joe Kelly and Jeff Arrillaga and JLL brokers Mark Bodie and Toss Valentine represented from JLL were the listing agents for the Catalyst project. LinkedIn was represented by Colliers.

Together, these leasing and purchase transactions point to a remarkable — and ongoing — major expansion in Silicon Valley for LinkedIn.

And the transactions could bring Sunnyvale as many as 2,900 jobs.

The buildings on the sites that LinkedIn bought were slated for availability by the end of 2023, according to a brochure for the three-building campus.

A real estate alliance of real estate firms Harvest Properties and Invesco Advisors that are operating as a group called Sunnyvale Owner sold the two sites on West Maude Avenue to LinkedIn.

In addition, Harvest and Invesco jointly developed and own the building that LinkedIn leased on West Maude.

The LinkedIn transactions, along with an array of major recent leasing and property purchase transactions involving multiple tech titans suggest that tech companies are not fleeing Silicon Valley en masse as some pundits have prognosticated.

Instead, tech companies of varying sizes — including the largest firms — have taken steps lately to strengthen their footholds in Silicon Valley.

Among the recent major deals:

— Meta Platforms, whose apps include Facebook, leased 719,000 square feet in northern Sunnyvale at a four-building campus near the corner of Crossman Avenue and Caribbean Drive.

— Meta also leased 520,000 square feet in Burlingame on Airport Boulevard in a project known as Peninsula Innovation Point, in a deal also revealed on Wednesday.

— Apple in March leased 698,000 square feet at Sunnyvale’s Pathline Park, agreeing to rent several buildings in a deal arranged by commercial real estate firms CBRE and Cushman & Wakefield.

— Apple is also pushing forward with a new campus in north San Jose.

— Apple in September paid $450 million for five office buildings in Cupertino, all near the interchange of Interstate 280 and North De Anza Boulevard.

— Tesla has rented a big office building in Palo Alto, a deal that was made even after the electric vehicle manufacturer’s chief executive Elon Musk said the company would move its headquarters to Texas. Tesla is keeping its vehicle factory in Fremont, at least for now.

— Google is pushing forward with a big new mixed-use neighborhood in downtown San Jose, new office hubs in north San Jose, and major development projects that will create campuses in Mountain View and Sunnyvale.

— Adobe is constructing a new office tower that would dramatically expand its current three-highrise headquarters campus in downtown San Jose.

— Intuitive Surgical is pushing ahead with a huge new campus in Sunnyvale totaling 1.21 million square feet and also has spent at least $109.1 million for properties that could enable further expansion.

— Fortinet has spent $80 million from 2012 through early 2021 buying a slew of properties in a push to create elbow room in its home territory of Sunnyvale.

— Applied Materials has bought properties and buildings in Sunnyvale in a shopping spree that tops $190 million in recent years.

And it also appears that the tech boom and rising office rents in Silicon Valley have enticed investors to gobble up numerous large chunks of properties in Silicon Valley.

In San Jose, investment giant AGC Equity Partners paid $780 million for three buildings in a section of the Coleman Highline mixed-use tech campus in north San Jose. The deal by London-based AGC represented the most money paid for a Silicon Valley property so far in 2021 in a single transaction.

The expansions by the tech companies are deals that are poised to do much more than merely reduce office vacancy rates: They represent potential big increases in the Silicon Valley job base.

The office building at 684 W. Maude that LinkedIn leased could accommodate 800 to 1,000 workers.

The nearby sites that LinkedIn purchased have older office buildings that will be demolished and replaced with two new office buildings, which each total 188,800 square feet.

That means LinkedIn could place 1,500 to 1,900 workers in the buildings that would sprout on the just-purchased parcels.

The entire campus of three buildings, if all are occupied, could contain 2,300 to 2,900 LinkedIn workers, once the final two buildings are completed.

The Catalyst developers crafted the tech campus with an eye on protecting workers from the coronavirus and other viruses.

“Tenants will have the ability to integrate customized space design features on top of a thoughtfully architected, COVID friendly base building to optimize the workplace for their employees,” Harvest and Invesco stated on the Catalyst project website.