Facebook shares have ended flat on the first day of trading, dampening optimism over the hotly-anticipated debut for the world's biggest social network.
The shares, priced at $38 (£23.95) on Thursday in the largest-ever initial public offering (IPO), failed to flourish in price on the Nasdaq in New York.
They eked out a fractional gain of just 0.97% to end at $38.37 (£24.19), with record volume of more than 550 million shares traded.
"It is a pretty underwhelming start for Facebook and a problem for the much-vaunted launch on the Nasdaq," Sky's Dominic Waghorn, reporting from Times Square, said.
The damp end to the day also saw a slow start - as a half-hour delay due to technical problems had investors grumbling.
"The Nasdaq seems to have a lot of questions being asked of it by disgruntled investors," Waghorn said.
Facebook's chief executive Mark Zuckerberg, who created the website in his Harvard University dorm room in 2004, sold about 30 million shares, pocketing $1.15bn (£724.6m) in the process.
He will retain a controlling stake in the company, making him worth an estimated $19.1bn (£12bn) - the 23rd richest person in the world - at the age of 28.
Around 1,000 millionaires were also expected to be created by the flotation , including a small number of the 100 London-based staff.
"As for Mark Zuckerberg, he has made a lot today and his company is valued at over $100bn," Waghorn said.
"However, there will be concerns on why there was not a significant price rise on the day."
If Mr Zuckerberg was disappointed in the public reception, he did not reveal it on his personal Facebook page .
Instead he said: "Right now this all seems like a big deal. Going public is an important milestone in our history.
"But here's the thing - our mission isn't to be a public company. Our mission is to make the world more open and connected."
The price per share peaked at $43.02 (£27.12), up on the pre-trade valuation of £24 in the IPO.
But it quickly fell back to $38.01 in the late morning before showing modest gains mid-afternoon to around $41 (£25.85).
In late afternoon trading it dropped down again to just above the opening mark before a modest climb to the close.
The listing on the Nasdaq as FB valued the social networking website at $104bn (£66bn) - bigger than Amazon , Disney , McDonalds or the Ford Motor Company.
And the sale of 421 million $38 shares is thought to have netted up to $18.4bn (£11.6bn) for the company.
Early seed investors such as U2 frontman Bono stand to make huge sums, with some predicting the singer - who reportedly owns 2.3% of the behemoth - becoming the richest rock star on the planet.
But as the rocker arrived in Washington DC for a fundraiser to help US President Barack Obama , he was asked about the instant riches.
The Irish singer chuckled and said: "I don't think it is true."
But James Hughes, chief market analyst at Alpari UK, said: "The real value of Facebook is not likely to be known until the hype of the IPO has died away and investors have been able to digest how the company is going to evolve to be the money making machine many expect it to be."
Facebook has more than 900 million users worldwide who log in at least once a month, but it makes only a few dollars per year from each one, chiefly through advertising that will increasingly need to be accurately targeted.
:: Facebook is being sued in the US over alleged breach of privacy, in a class action filed by a number of its members.