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 energy efficiency company Ameresco (AMRC -0.27%) fell as much as 20% today, after reporting third quarter results.

So what: Revenue fell 28.1% from a year ago to $163.9 million, and was far below the $196 million mark that analysts expected. Earnings per share of $0.15 were $0.08 below estimates, and the company also lowered guidance for the rest of the year.

Now what: Management blamed a lengthening of backlog conversion times due to customer uncertainty as having a big impact on the second half of 2012. Results are expected to improve as the political environment becomes clearer after the election.

The third quarter wasn't good in any way for Ameresco, but I wouldn't take the stock off my watchlist entirely. Even lower guidance puts the company's P/E ratio around 20 and, if demand picks up after the fiscal cliff and other urgent political matters are resolved, the company could return to solid profitability. I'm not a buyer today, but further dips in the stock may be an opportunity to buy for long-term investors.

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