Facebook founder and CEO Mark Zuckerberg and his long-time girlfriend Priscilla Chan tied the knot at a small ceremony at his home in Palo Alto, California, a day after $104 billion IPO.

Priscilla Chan, 27, also had a busy week, graduating from medical school on Monday, as Zuckerberg marked his 28th birthday.

The guests believed they were going to celebrate Priscilla Chan’s graduation – but found they were at a wedding instead.

The wedding ring, a “very simple ruby”, was designed by Mark Zuckerberg.

Mark Zuckerberg weds Priscilla Chan in secret ceremony after $104 bn IPO

Nine years ago the pair met at Harvard, where Mark Zuckerberg founded Facebook in 2004.

They later moved to California, where Facebook has its headquarters, and Priscilla Chan studied at the medical school of the University of California, San Francisco.

Facebook’s valuation after its flotation on Friday means the social network site is worth about the same as internet shopping giant Amazon, and more than the value of stalwarts such as Disney.

Even after the flotation, Mark Zuckerberg continues to control just under 56% of the voting power of the company.