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 World Wrestling Entertainment (NYSE:WWE) plunged nearly 15% Monday after the company provided an update on subscriber numbers for its new streaming network.

So what: Specifically, just 42 days after launching the WWE Network in the U.S., World Wrestling Entertainment said it already has 667,287 subscribers, making it "the fastest-growing digital subscription service." For perspective, WWE previously outlined a goal of reaching 1 million subscribers -- or what management called its breakeven point -- by the end of 2014.

The news comes on the heels of WWE's sold-out WrestleMania 30 event, which aired live Sunday on WWE Network as well as on pay-per-view.

For $9.99 per month and a minimum six month-commitment, the WWE Network provides subscribers streaming online access to both live and scheduled WWE programming, including 12 live pay-per-view events and a comprehensive video-on-demand library.

Now what: However, investors remained concerned as some estimates pegged WWE Network's initial rush to drive as many as 800,000 to 1 million early subscribers by the time WrestleMania 30 concluded. What's more, a Barron's piece this weekend called out WWE on worries the attractively priced service might not make up for the company's resulting drop in pay-per-view revenue.

In any case, we should know more about whether that's actually the case when pay-per-view numbers for WrestleMania 30 are released in a few weeks. Until that happens, I think investors would be wise to refrain using this drop as a buying opportunity.