CEO Mark Zuckerberg and Priscilla Chan at their wedding ceremony in Palo Alto, CA

Zuckerberg and 27-year-old Priscilla Chan tied the knot at a small ceremony at his Palo Alto, CA, home, capping a busy week for the couple, according to a guest authorized to speak for the couple. The person spoke only on the condition of anonymity.

Zuckerberg took his company public in one of the most anticipated stock offerings in Wall Street history Friday. And Chan graduated from medical school at the University of California, San Francisco, on Monday, the same day Zuckerberg turned 28, the person said.

The couple met at Harvard and have been together for more than nine years, the person said.

Zuckerberg designed the ring featuring “a very simple ruby,” according to the person.

The ceremony took place in Zuckerberg’s backyard before fewer than 100 guests, including Facebook’s chief operating officer Sheryl Sandberg.

The guests all thought they were coming to celebrate Chan’s graduation but were told after they arrived that the event was in fact a wedding.

“Everybody was shocked,” the guest said.

Rather than his trademark hoodie, Zuckerberg wore a suit for the ceremony, while his bride wore a traditional wedding dress.

Food was served family-style and included dishes from the couple’s favorite Palo Alto sushi restaurant. The two had been planning the marriage for months but were waiting until Chan had graduated to hold the wedding, the guest said.

The timing wasn’t tied to the IPO, since the date the company planned to go public was a “moving target,” the guest said.

Even after the IPO, Zuckerberg remains Facebook’s single largest shareholder, with 503.6 million shares. And he controls the company with 56 percent of its voting stock.

The site, which was born in a dorm room eight years ago, has grown into a worldwide network of almost a billion people.