On Thursday, the stock market returned to its winning ways, with the S&P 500 once again making it into record territory. Without any obvious negative news, investors continue to bid up share prices slowly but steadily, and even news that the revised reading on gross domestic product in the U.S. fell by 1% in the first quarter wasn't enough to quash optimism about the prospects for stocks, at least in the short run. Many stocks posted substantial gains, with BlackBerry (NYSE:BB), Clean Energy Fuels (NASDAQ:CLNE), and Solazyme (NASDAQ:TVIA) among the top performers today.

BlackBerry gained 6% after CEO John Chen once again emphasized his belief that the long-struggling mobile-device pioneer has every chance of recovering in the long run, arguing that the company now has an 80% chance of successfully turning its business around. Few investors expect BlackBerry's legacy smartphone business to reclaim anything close to the market share it once commanded, given the heavy competition around the world in every niche of the mobile market. But Chen's moves to emphasize BlackBerry's software offerings have opened the door to higher-margin business opportunities that have the potential to drive profits. If BlackBerry can convince potential enterprise clients to see its products as a viable alternative to those of its competitors, then the stock's gains today could be just the tip of the iceberg.

Source: Clean Energy Fuels.

Clean Energy Fuels climbed 9% after the natural-gas fueling specialist got favorable coverage from a Wall Street analyst. The analyst set its initial rating on Clean Energy Fuels at Overweight and put a $14 price target on the stock, which still represents roughly 25% upside even from levels after today's run-up. The potential for explosive growth in the natural-gas fueling market is huge, given the price disparities between oil-based fuels and natural gas and the rise in technology allowing even heavy-duty trucks to use engines that run on the clean-burning fuel. Clean Energy Fuels still has to survive emerging competition in the area, but it has the inside track with a head-start on its would-be rivals.

Solazyme rose 7% after the maker of renewable oils announced that its Brazil production facility began commercial production of its algae-based oil products. The facility, which is located in Moema, will have full capacity of about 100,000 metric tons annually. The start-up comes after delays that pushed back the timeline from initial estimates of the first quarter of 2014. Given the huge ramp-up the Brazil-based plant will offer compared to its existing capacity, the big question facing Solazyme is whether there'll be enough demand to keep prices high even as supply expands.

Dan Caplinger has no position in any stocks mentioned. The Motley Fool recommends Clean Energy Fuels. The Motley Fool owns shares of Solazyme. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.