It's also believed to be a record for security costs for any CEO of a large corporation. Equilar, the compensation research firm, said it was the largest amount it's seen "by a wide margin" for any Fortune 100 company in the last five years.



Facebook also spent $1.5 million on private jet travel, up from $871,000 in 2016.



How does Zuckerberg's security budget stack up against other billionaires? It's not even close.



Amazon spent $1.6 million in 2016 on security for Jeff Bezos, the world's richest man. Oracle spent about the same amount on security for Larry Ellison in 2016. Apple spent just $224,000 on security for Tim Cook and Berkshire Hathaway spent $387,000 on security for Warren Buffett.



Facebook doesn't say exactly how it spent the money, such as number of security guards or type of equipment used. In the filing, the company said the security program was "to address safety concerns due to specific threats to his safety arising directly as a result of his position as our founder, Chairman, and CEO." The company added that it paid for "the initial procurement, installation, and maintenance of security measures for Mr. Zuckerberg's personal residences, and we pay for the annual costs of security personnel."



Security companies to the wealthy say that while Zuckerberg's expense is high, it's not unprecedented. They said many companies allocate security expenses differently to minimize the reported number. And they said many private companies run up big security tabs that never get publicly reported.



"The average American might look at that price tag and say 'my gosh,'" said Mark Haught, president of Gavin de Becker & Associates, a leading security firm to celebrities, billionaires and public figures. "But you're talking about the safety and security for you and your family and key executives who help run a massive company."



He said the costs of a security program go far beyond bodyguards. It also includes "risk assessment," which can be everything from background checks to travel planning and assessments and information on people the executive may be meeting with.



"It's a lot of logistics, planning and preparing," he said. "These people have very complex lives and logistics plays a big part."



One possible reason Zuckerberg's security tab soared so much last year was his road trip across America. He said he planned to visit all 50 states and learn more about how people lived and worked. Each of those trips would have required an advance security team to scope out the visit and people he planned to meet. He visited factory workers, opioid addicts, farmers and Americans of all types.



As it turns out, seeing everyday Americans is expensive for a billionaire.