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 Marrone Bio Innovations (MBII) jumped 11.5% today after an analyst initiated coverage on the bio-based best management and plant health company.

So what: Investment firm Robert W. Baird began coverage with an outperform rating and a $15 price target on the stock. The price target represents a 43% upside based on Friday's closing price.  

Now what: Analyst upgrades or downgrades can have a short-term impact on stocks, but over the long term they shouldn't change your investment thesis. In fact, Wall Street analysts have a long history of underperforming the market and don't even have much of an incentive to get their picks right. If you're interested in buying shares, wait for this short-term pop to subside and get in at lower levels.