The largest office building in Oakland is up for sale.

Spanning nearly 1 million square feet, 300 Lakeside Drive, previously known as Kaiser Center, could set a record price as the city’s biggest property sale.

Owners the Swig Co. and Rockpoint Group told The Chronicle they are marketing the “highly desirable, transit-focused urban campus” in a market with few vacancies for growing companies.

“300 Lakeside is one of a very few Bay Area locations where a large tenant can access near-term, large block creative space as well as the long term ability to grow in one of the Bay Area’s most dynamic and accessible corporate locations,” said the Swig Co.

An asking price wasn’t disclosed, but nearby towers have sold for more than $600 per square foot, suggesting 300 Lakeside’s price could exceed $600 million. That would be about triple what Swig paid for the complex in 2005, a testament to Oakland’s surging real estate market.

The tower was built in 1960 as the headquarters of Kaiser Industries, the construction and shipyard conglomerate whose health care operation was a predecessor to Kaiser Permanente.

The building is 98% leased, but numerous tenants are now planning to move out, giving a new owner the opportunity to substantially increase rents. BART is headquartered in more than a third of the building and plans to depart by 2021 for a nearby building at 2150 Webster St. BART says its rent would roughly double from $40 per square foot annually if it stayed.

The University of California Office of the President and Kaiser Permanente are also leaving as they prepare to move into new buildings elsewhere. In total, 70% of the tower will become vacant between 2021 and 2024.

Swig and Rockpoint previously completed a lobby renovation to attract new tenants. They also proposed building two additional towers on the property totaling 1.3 million square feet, which a new owner could pursue.

Alexander Quinn, Northern California research director at brokerage JLL, said a new owner could invest in major renovations as tenants leave 300 Lakeside, which could draw major new companies to the area. The project accounts for 11% of Oakland’s Class A, top-quality office space, and new tenants could have ripple effects by drawing others to nearby buildings, he said.

“Any investments to this property would have a meaningful impact on the overall Oakland market simply by its sheer market share,” said JLL’s Quinn. A major tech tenant would further transform the city’s economy, he said.

“Whatever happens, the sale will be a barometer for Oakland’s overall office market,” Quinn said.

Roland Li is a San Francisco Chronicle staff writer. Email: roland.li@sfchronicle.com Twitter: @rolandlisf