Mark Zuckerberg

Mark Zuckerberg's relationship status has changed.

One day after taking Facebook public, the company's founder married his girlfriend, Priscilla Chan, Saturday in Palo Alto, Calif., People reports.

The intimate backyard ceremony was a surprise to the less than 100 guests in attendance, who thought they were going to a surprise party to celebrate Chan's recent graduation from the University of California, San Francisco, where she received her degree in pediatrics last week.

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Zuckerberg, 28, and Chan, however, had been planning the wedding for more than four months. Zuckerberg designed his bride's ruby wedding ring.

Guests enjoyed food from the couple's favorite restaurants, Palo Alto Sol and Fuki Sushi, as well as chocolate mice (yes, chocolate treats made in the shape of mice) that Zuckerberg and Chan had on their first date.

The couple, who met while attending Harvard, dated for more than nine years.