Public records show, Zuckerberg has re-financed his $6 million Palo Alto home with a 30-year adjustable rate loan starting at 1 percent.
While all lending rates are near historic lows right now, experts say high net-worth individuals can pay even less using adjustable rates. Most people can't afford the risk of a large increase later on, so they lock in a higher interest rate.
Zuckerberg is the world's 40th wealthiest person, worth $15.7 billion.
