Facebook CEO Mark Zuckerberg is so rich that he's living in his $5.95 million Palo Alto home at short-term cost close to $0.

In other words, for free.

Zuckerberg just re-financed his home with a 30-year adjustable-rate loan starting at 1.05 percent, according to Bloomberg's John Gittelsohn and Dakin Campbell.

Because 1.05 percent is below the current rate of inflation – somewhere between 2 and 3 percent – Zuckerberg is essentially "borrowing for free," Greg McBride, senior financial analyst with Bankrate Inc, tells Bloomberg.

Zuckerberg is taking the mortage because the interest rate is so low that he can invest the cash he would have spent on the house, risk-free, and get a higher rate of return than the rate at which he is borrowing.

Zuckerberg gets such a nice rate because he took an "adjustable rate," which means the bank can crank it up if it wants. 

Bloomberg says the average rate for a 30-year fixed low is 3.56 percent. Meanwhile, the average rate for a one-year adjustable loan is 2.69 percent.

Zuckerberg's rate beats that figure because his bank, First Republic, figures he's good for the money; he is the world's 40th richest person, after all.

“First Republic, like most banks, prices its credit products based on the strength and totality of the entire client relationship,” a bank spokesperson told Bloomberg. “This is our approach with all of our clients.”

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