The first surprise was learning that billionaire Facebook founder Mark Zuckerberg even has a mortgage.

The second was finding out that he pays an interest rate of just 1.05%.

Zuckerberg recently refinanced the 30-year mortgage on his $5.95 million five-bedroom, 5-1/2-bath home in Palo Alto, Calif., through First Republic Bank (FRB) in San Francisco, Bloomberg reported on Monday, citing a document filed with the Santa Clara County Clerk-Recorder's Office.

Zuckerberg's new loan replaced an adjustable-rate mortgage from Morgan Stanley (MS) that was recorded in June 2011 with a 1.75% rate, according to Bloomberg. The wire service reported that mortgage payments on the property now start at $19,275 a month, down from $21,256 for the old loan.

Some media reports praised the brilliance of the billionaire for keeping the low-rate mortgage, which beats the cost of inflation, and getting a higher rate of return elsewhere by investing the excess cash that normally would have been spent on the home.

Reuters' Felix Salmon surmised that Zuckerberg was so annoyed at Morgan Stanley for botching Facebook's IPO that "he severed his relationship with the bank," paid off his loan in full and moved his mortgage to a rival bank.

While it may be hard to resist bashing the 1% for getting a sweet 1% rate on their mortgage, it's hardly a surprise that banks specializing in high net worth individuals would woo the social network founder with such favorable terms.

"First Republic, like most banks, prices its credit products based on the strength and totality of the entire client relationship," said Greg Berardi, a spokesman for First Republic. He declined to comment on specifics of the loan or the bank's relationship with Zuckerberg.

The home, which is located about three miles from Facebook's Menlo Park headquarters, cost $7 million when Zuckerberg bought it last March in the name of a limited liability company, Bloomberg reported.

He got married to his longtime girlfriend Priscilla Chan in the home's backyard on May 19. The surprise wedding was held the same week as Facebook's initial public offering.