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 Warner Music Group (NYSE: WMG) sank as much as 14% in intraday trading Tuesday after its quarterly revenue came in well below analyst expectations.

So what: Warner Music's first-quarter loss widened as sales dropped 14% to $789 million, versus the average analyst estimate of $798 million. The music industry continues to struggle mightily in the face of withering compact disc demand, with today's quarterly loss marking the eighth straight for Warner Music.

Now what: I'd continue to leave Warner Music alone. Even the company's digital sales, its lone bright spot over the past few years, showed clear signs of slowing down. Unfortunately for Warner Music, along with other recording companies like Vivendi's Universal Music Group and Sony's Sony Music Entertainment, it looks like the transition from CDs to digital music will remain a bumpy one for quite some time.

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