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Reuters
Uber entered a new era as a publicly listed firm on Friday, but shares fell in early trading to $42 (£32.20).
Boss Dara Khosrowshahi was among those who rang the opening bell of the New York Stock Exchange to begin trading.
Against the backdrop of a US-China trade spat hitting Wall Street, shares sank below the company's listing price.
On Thursday, the ride-hailing app sold 180 million shares at $45 each, raising $8.1bn of fresh cash and valuing Uber at $82bn (£63bn).
Shares in the company opened at $42, and skidded to as low as $41.06 early on. Stock recently trading around $43.90, still 2.4% down on the list price.
Uber is yet to make a profit and warned recently it may never do so.
Since its foundation in 2009, the company has lost about $9bn.
Uber had originally suggested a price range of $44-$50 for its share price listing, valuing the company at up to $120bn.
Mr Khosrowshahi said the $45-a-share float price was influenced by the uncertainty in the global economic environment.
Shares will now trade under the symbol UBER, after the most anticipated US debut since Facebook in May 2012.
Uber co-founder Travis Kalanick, who departed the chief executive role to make way for Mr Khosrowshahi after questions were raised about staff culture at the firm, was also present at the exchange for Uber's debut.
Investors are betting on Uber's growth prospects as it diversifies into several other sectors. As well as the original ride-hailing business, Uber is developing driverless cars and has a food delivery operation, Uber Eats.