Exxon Mobil Corp.'s $10.89 billion first-quarter profit report Thursday ranks as one of the biggest hauls in U.S. corporate history. But the results disappointed Wall Street and added to concerns about the future of the industry.

Exxon, the world's biggest non-government controlled oil company by market capitalization, notched a 17.3% increase in profit over the year-earlier period largely from the surge in oil prices, which set new records earlier this year. Yet the earnings discouraged investors, who at one point sent Exxon shares down as much as 5.1% in intraday composite trading on the New York Stock Exchange, the stock's largest one-day drop since January. At 4 p.m., its shares finished at $89.70, down $3.37, or 3.6%.

Among the biggest concerns: A number of factors conspired to affect production, pushing down the number of barrels pumped by 9.9% from a year earlier.

Exxon Mobil 's head of investor relations, Henry Hubble, conceded the quarter was a rare "miss" for the energy giant, with earnings falling about $600 million short of analysts' predictions. It was all the more disappointing to investors because surprisingly strong earnings reports by BP PLC and Royal Dutch Shell PLC earlier this week had raised hopes Exxon also would exceed expectations.

The soaring profits from fossil-fuels are coming as the rules for the industry are being rewritten, pressuring oil companies to move beyond fossil fuels to new sources of energy. With new finds rare and the best sources in countries that limit Western investors, crude oil is no longer viewed as the abundant, dominant fuel it once was. Critics contend that unless these companies focus more on the future, today's record profits could dry up.