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 American Railcar Industries (Nasdaq: ARII) slid 10% today after an analyst downgrade.

So what: KeyBanc Capital Markets was the culprit today, downgrading the stock from a buy rating to a hold. The company cited a shift to leasing as a reason it thought American Railcar would miss estimates in the near future.

Now what: The report didn't really expose any flaws in the business and instead focused on how analysts would probably be conservative with their estimates because of the modeling change in the leasing business. We Fools don't usually put a lot of faith in analysts, and this downgrade seems especially suspect. If you're a long-term investor, I wouldn't be afraid to look at this as a buying opportunity, because nothing about the investment thesis has changed, and now the stock is 10% cheaper today.

Interested in more info on American Railcar Industries? Add it to your Watchlist.