Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of fuel-cell maker Plug Power Inc. (PLUG 6.43%) jumped another 15% today, touching a new 52-week high after being upgraded by an analyst.

So what: Cowen and Co. increased their price target on the stock to $5.50 from $5 and said the recent fuel-cell deal with Wal-Mart could be replicated with other large distributors. The analysts are expecting more such contracts and said the recurring revenue from such deals will be significant.  

Now what: Before going out and buying shares on this analyst note, keep in mind that shares closed yesterday above the $5.50 price target. The company's market cap currently stands at $686.4 million and revenue over the past 12 months was just $24.5 million. There's going to need to be a massive improvement in operations very quickly to justify that valuation, which will keep me out of the stock today.