Shares in social network Facebook immediately jumped 13% to $42.99 on their first day of trading, after the company's initial public offering (IPO).
Trading of the shares on the Nasdaq stock exchange was delayed by around half an hour, but the first trades eventually began at 11.30am eastern standard time.
Facebook's shares were initially offered to the public for $38, and the company - valued at $104bn - took in $18.4bn from the sale.
Zuckerberg opened the stock exchange by remote control from Facebook's HQ at 1 Hacker Way in California.
He pressed the button in front of a cheering crowd of employees, surrounded by Facebook execs and to the soundtrack of an apparently slightly-warped loop of dramatic music.
Facebook's engineers apparently hacked the Nasdaq button before the sale, so that the message "Mark Zuckerberg has listed a company on NASDAQ - FB" was automatically posted to his Facebook Timeline.
Before the opening bell Facebook hosted its 31st 'Hackathon' event to develop new ideas and products.
Trading is set to begin under the ticker symbol FB two days after massive interest in the sale prompted the company to boost the number of shares it plans to sell, with 84m more being added to the IPO.
Investors such as U2 frontman Bono stand to make huge sums, with music magazine NME predicting the singer will become the richest rock star on the planet when the company floats.
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Predictions on how much the stock will rise on the first day of trading vary greatly.
Shares of professional networking company LinkedIn Corp's doubled on their first day of trading but despite the hype, scepticism remains in some quarters, with murmurings that the stock is overvalued.
In a recent Bloomberg survey of 1,250 global investors, analysts and traders, 79% said Facebook's valuation was not justified, with only 7% deeming the valuation fair.
