What happened Extending the 7% rise that they had been on through the close of yesterday's trading session, shares of Plug Power (NASDAQ: PLUG) are bounding even higher today. As of 11:16 a.m. EDT, the fuel cell specialist's stock is up 2.3%, retreating slightly from its 5.5% jump earlier in the day. Whereas yesterday's climb was attributable to overall enthusiasm for fuel cell solutions, investors are picking up shares today in reaction to news from Wall Street. Image source: Getty Images. So what Taking a more bullish stance on Plug Power's stock, Pearce Hammond, an analyst at Piper Sandler, upgraded the stock to overweight from neutral, keeping the price target at $33. Based on yesterday's closing price of $26.92, the $33 price target represents upside of about 23%. Investors are likely responding enthusiastically to the analyst's upgrade as it's the second one the company's received this month. In the beginning of September, Wolfe Research initiated coverage on the stock with an outperform rating and a $34 price target. Now what Like the analysts on Wall Street, those on Main Street are extremely optimistic about Plug Power's prospects, making it one of the most popular stocks discussed among investors. That popularity continues to remain strong in the light of J.P. Morgan's recently revealed belief that the company is on track to meet its billings targets for 2021 and 2022. Despite the optimism that surrounds the stock, potential investors should recognize that there are still plenty of risks -- such as a lack of profits and positive cash flow -- that surround this growth stock; therefore, they should tread with caution before adding Plug Power to their portfolios. 10 stocks we like better than Plug PowerWhen our award-winning analyst team has a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* They just revealed what they believe are the ten best stocks for investors to buy right now... and Plug Power wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of September 17, 2021 JPMorgan Chase is an advertising partner of The Ascent, a Motley Fool company. Scott Levine has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source