He made his fortune by persuading over a billion people to share their lives online, but when it comes to protecting his own privacy Mark Zuckerberg appears to spare no expense: the Facebook founder has reportedly spent US$30 million buying four houses that surround his own home in California.
Zuckerberg acted after hearing that a developer planned to buy an adjoining property and market it as an opportunity to become neighbours with him.
"The developer was going to build a huge house and market the property as being next door to Mark Zuckerberg," a source told the San Jose Mercury News.
The buying spree began in December, several months after Facebook's flotation elevated Zuckerberg into the ranks of America's super-rich, and culminated this week with the sale of a property immediately next to the home he shares with his wife, Priscilla Chan.
Chan also own a house in the Dolores Heights district of San Francisco that they bought this year for about US$10 million and have been renovating for US$1.6 million.
The transactions suggest the multi-billionaire has spent many times the US$7 million cost of his own home, bought two years ago in a leafy neighbourhood of Palo Alto in the heart of California's Silicon Valley.
In an effort to keep the purchases under the radar, the party named on the deeds is not Zuckerberg himself, but companies affiliated to Iconiq Capital, a wealth management firm that represents the Facebook chief executive and a number of other tycoons.
Rather than being demolished to extend the digital entrepreneur's own estate, the homes are apparently being leased back to the families that live there - with the interested parties required to sign non-disclosure agreements.
Despite a fortune estimated at US$19 billion, the 29-year old is known for living modestly, having rented for years before taking the plunge into northern California's overheated property market. But the size of Zuckerberg's reported land grab brings him into line with Silicon Valley's flashier inhabitants.
"It's 10 times more than a typical house," property agent Alex Comsa told Silicon Valley Business Journal. "It's unheard of."
Additional reporting by Bloomberg