Employees at Dublin’s Facebook European headquarters stand to gain six-figure windfalls after the company went public on Friday.

A valuation of over $100 billion will give many of the 400 staff in Ireland’s capital a stake worth several thousand euro.

Founded by Mark Zuckerberg in a Harvard University dorm room in 2004, Facebook share options are available for most employees who currently own around 30 percent of the company.

Just five days after his 28th birthday Zuckerberg, the chairman and CEO, rang the bell of the New York Stock exchange officially opening the company on the Nasdaq stock market. More than 300 million shares traded within the first two hours. The billionaire rang the virtual bell from Facebook headquarters in Menlo Park, California.

The social media website has a market value of more than $104 billion and is offering shares to the public for $38 in one of the most hotly anticipated US stock flotations.

Bono was one of the many Facebook shareholders who benefited from Friday’s flotation. In 2009 his Elevation Partners equity firm bought 2.3 percent of the company.

The rock and roll star’s investment is estimated to be worth over $1.5 billion now that the company is public.

Facebook has more than 900 million active users around the world.  The company reported an average of 526 million daily active users in March 2012. With offices around the world the social networking giant currently employs around 3,500 people. The company opened its Dublin offices at Grand Canal Dock in 2008 and hired an extra 100 staff last year.

Mark Zuckerberg rings the NASDAQ bell before Facebook IPO: