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: Ameresco, Inc. (NYSE: AMRC) dropped 12% in intraday trading today after the energy services company's fourth-quarter EPS beat by $0.02 but 2011 guidance fell short of consensus expectations.

So what: Compared to the year-ago quarter, fourth-quarter revenue grew 34%, operating income grew 11% and net income fell -- yes, fell -- 20%. Increases in cost of sales, interest expenses, the effective tax rate, and the share count (related to last October's IPO) all contributed a whopping 37% decline in EPS.

Now what: The mid-point of 2011 guidance calls for growth of 13% in revenue, 14% in EBITDA, 25% in net income and 12% in EPS. The higher share count from the IPO will anniversary out in October 2011, setting the stage for better EPS growth in 4Q11 and 2012. That said, the forward P/E ratio of 19.1x looks steep for a company with revenue and EBITDA growing at a low-teens rate and EPS that is sensitive to fluctuations in interest rates and foreign currency.

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