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 cemetery-services company StoneMor Partners (Nasdaq: STON) were getting buried by the market today, falling as much as 17% even as the broader market rallied.

So what: In a press release following the close of trading yesterday, Standard & Poor's put StoneMor's credit rating on a negative watch, sparking concerns that it would be downgraded to below its current B level. At the same time, S&P downgraded the unsecured debt of StoneMor's subsidiary from B- to CCC+.

Now what: While both the company's credit rating and the rating on the subsidiary's notes were already well below investment grade, lower ratings are not a happy outcome for a company whose stated EBITDA -- a cash-flow measure -- is already barely covering its interest commitments.

Looking ahead, investors will want to see the company make progress toward improving its balance sheet and stabilizing its financing. If ratings agencies and bond investors continue to bite their nails over StoneMor's financial stability, yesterday's warning could become a downgrade, which could put the company in an even tougher financial position.

Of course, as my fellow Fool Alex Pape outlined back in August, there may be more than meets the eye when it comes to StoneMor's financials, so the S&P's take may not be quite as bad as it seems at first blush.

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