The success of an internet company has combined with a drop in oil prices to send the US stock market higher.
Shares of social networking company LinkedIn jumped 109% to 94.25 US dollars on the first day they began trading on the New York Stock Exchange.
The debut is seen as a preview of other social networking sites that are expected to start trading during the next year. The list of candidates includes the online messaging service Twitter, game maker Zynga, and the biggest social network of all, Facebook.
"LinkedIn represents the first opportunity for the average investor to participate in what looks like a lasting, powerful trend of social media," said Lawrence Creatura, a portfolio manager at Federated Investors. "They're frothy with excitement, and that's being imputed into the share price."
LinkedIn finished Thursday with a gigantic price-to-earnings ratio of 554, a valuation reminiscent of internet stocks during the late 1990s technology bubble. By comparison, the average price-to-earnings ratio of tech companies in the S&P 500 index like Apple and Google is 15.
Sumeet Jain, a principal with venture investing firm CMEA Capital, said LinkedIn's IPO suggests that the number of mergers and acquisitions will increase this year as social networking companies grow, a potential boon for the stock market.
LinkedIn is "going to have to be quite aggressive" to meet investors' lofty expectations, Mr Jain said. "All the rest of the companies in the pipeline, when they're all public companies they will be extraordinarily active acquirers as well."
The Dow Jones industrial average rose 45.14, or 0.4%, to close at 12,605.32. The S&P 500 gained 2.92, or 0.2%, to 1,343.60. The Nasdaq composite index rose 8.31, or 0.3%, to 2,823.31.
Oil prices fell back below 100 dollars a barrel after an international agency said there is an "urgent need" for refineries to produce more gasoline and bring down pump prices in order to prevent a downturn in the global economy. Delta Air Lines rose 4.1% and JetBlue Airways rose 1.4% on expectations that their fuel costs would decrease.
Oil prices have fallen about 13% since the beginning of May as part of a broad-sell off in commodities due to fears that the economy is slowing. Despite LinkedIn's gains, concerns about the economy weighed on the market again.
Press Association