According to city documents and property sources, Apple could move nearly 1,500 workers to a newly-acquired campus in Sunnyvale.
The 290,000 square foot complex, known as Sunnyvale Crossing, was purchased by Lane Partners to be renovated into a state-of-the-art office campus.
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This latest development comes during construction of a 2.8 million square foot campus in Cupertino that could be used to accommodate 14,200 Apple workers.
Tim Bajarin, a principal analyst with Creative Strategies, thinks that the expansion is "more than justified," after the company earned $37.71 billion (£22.4 billion) on $176 billion (£104 billion) of revenue over the last 12 months.
"Apple continues to grow," added Bajarin. "They are building e-commerce, support staff; they are adding new software and hardware products; they are hiring all sorts of high-level engineers."
City records currently list Apple as the tenant in one of the 69,000 square-foot buildings but sources say that the tech giant is planning to occupy the other six buildings too.
Mountain View-based Google has also followed suit by expanding into surrounding cities, such as Sunnyvale after running out of room near its existing headquarters.
Jennifer Garnett, a spokeswoman for the city of Sunnyvale has welcomed the development, saying, "If there is a word to describe Sunnyvale and Silicon Valley, it is evolution."