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 billboard operator Lamar Advertising (Nasdaq: LAMR) dipped 10% today after the company reported disappointing first-quarter earnings results.

So what: For the quarter, Lamar reported a 4.3% increase in revenue to $266.3 million but noted a substantially wider-than-expected loss of $0.25 per share to repay roughly $30 million worth of debt due in 2015. Even worse, Lamar forecast that its second-quarter revenue would come in around $303 million, which was slightly shy of Wall Street's forecast for $305.1 million.

Now what: This really isn't anything new for Lamar, which has been trading at an astronomical valuation, in my eyes, for years. Lamar has lost money in two of the past three years and is currently valued at 52 times forward earnings. This is the reason I highlighted the company as a stock worth selling back in February 2011. Time hasn't been kind to this company, and I still feel it represents a poor investment.

Craving more input? Start by adding Lamar Advertising to your free and personalized watchlist so you can keep up on the latest news with the company.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.