On Tuesday, the stock market began on a positive note, but comments from Federal Reserve Chairwoman Janet Yellen threw cold water on investors' faces and led to a pullback from most major-market benchmarks. Although the Dow finished in positive territory, broader-based indexes fell modestly, with Yellen highlighting overvaluation in areas like biotechnology as raising concerns among policymakers. Despite the uncertain tone on Wall Street, many stocks managed to press higher, with Plug Power (NASDAQ:PLUG), Mechel (NYSE:MTL), and JPMorgan Chase (NYSE:JPM) all performing well today.

Source: Plug Power.

Plug Power soared 16% as bullish commentary from an analyst firm reawakened hopes of a hypergrowth phase for the fuel-cell system company. Analysts at FBR argued that within the next three years, Plug Power might control 10% of the electric forklift market, a niche that has helped drive Plug Power's early results recently thanks to big orders from companies including the nation's largest retailer. Moreover, if Plug Power can gain better market share of similar warehouse equipment, then the company could finally have a sustainable path toward a growing business. Shareholders might remain skeptical given the stock's track record of spiking higher only to retreat, but Plug Power has an opportunity to move forward in a potentially valuable market.

Mechel rose 9% as the Russian mining giant came to a deal with a creditor to refinance part of the company's extensive debt. The loan restructuring with VTB Bank extends the payment schedule and maturity of loans totaling 33.8 billion rubles, or almost $1 billion at current exchange rates. Now, Mechel won't have to make initial payments on the loans until next April, with final maturity in 2018. Still, unless conditions in the global market for metallurgical coal start to improve, it's uncertain whether the deal will be enough to help Mechel's long-term outlook very much.

JPMorgan Chase finished up 3.5% after a strong earnings report that helped pace the market's overall gains early in the session. Even though the bank reported a drop in overall earnings and revenue, the declines weren't nearly as bad as investors had initially thought. Even JPMorgan's own prediction of a 20% drop in trading revenue turned out to be only a 14% fall, following similar positive news from its banking peers in their earlier-released quarterly reports. Uncertainties like the future direction of Fed policy could continue to hold back JPMorgan's performance, especially if they keep would-be trading clients on the sidelines. Still, JPMorgan has done a good job in recovering from the worst of the financial crisis and continues to make hard-fought progress.