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 Laboratory Corp. of America (NYSE: LH) -- better known as LabCorp, a laboratory testing diagnostic services provider -- sank as much as 12% after updating its 2013 full-year guidance and providing its preliminary 2014 guidance.

So what: According to LabCorp's press release, the company's 2013 full-year EPS forecast is on target to hit $6.90-$7.05, which is within the expectation range of current consensus estimates, with revenue growth of 3%. The wheels fell off the bus, however, with LabCorp's 2014 guidance which calls for just $6.50 in EPS -- well below the $7.56 that Wall Street was anticipating -- on 2% revenue growth. LabCorp listed multiple negatives that are expected to affect its performance in 2014, including an increasing number of Americans with high co-pays and deductibles, government reimbursement uncertainties, and the uncertainties related to the implementation of Obamacare.

Now what: While I'm certainly a fan of laboratory testing with an aging population, investors should already have had LabCorp on their yellow flag warning list for its tepid revenue growth. Over the very long term, this is a business that should see gains as the pathway from the lab setting to clinical research is drastically improving for biopharmaceutical companies. Unfortunately, there just aren't any visible catalysts that I see over the next couple of quarters, or even years, that make me excited about LabCorp, even after today's haircut. It's worth a watchlist add here, but the shroud of uncertainty that management conveys likely means more earnings warnings could be in the offing.