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 job board website Monster Worldwide (NYSE:MWW) fell as much as 15% today, and finished down 8%, apparently on two separate pieces of news.

So what: The employment-solutions company seems to be getting left behind by the likes of LinkedIn (NYSE:LNKD) and, now, Facebook (NASDAQ:FB), which announced a social jobs app on Wednesday that will allow users to browse more than 1.7 million job openings. Some of the listings come from Monster.com, but the move still underscores the fact that the job search market seems to be moving from traditional job boards to social networks like LinkedIn. Monster is starting to look more and more like a transitional technology. Separately, the company announced it hadn't found any potential buyers; shares had previously spiked when it said it would look into that option.

Now what: Monster already looked suspect before today's news, and the prospect of Facebook's competition should be another sign to run. Analysts seem to be exaggerating EPS growth in the next year, expecting it to nearly double to $0.43, despite a decline in revenue. This company only saw its shares jump earlier in the year on news that it would search for a buyer. Now that we know there's no company that wants to buy it, shareholders should take that news to heart.

Don't miss the next update on Monster.

Jeremy Bowman has no positions in the stocks mentioned above. The Motley Fool owns shares of Facebook and LinkedIn and has the following options: long JAN 2014 $20.00 calls on Facebook. Motley Fool newsletter services recommend Facebook and LinkedIn. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.