What's happening: Shares of ETF expert WisdomTree Investment, Inc (NASDAQ:WETF) were down about 10% at one point today, before making up some losses. As of this writing (about a half-hour before market close) the stock is down 8.8%.

Why it's happening: There's not any material news out today about the company, but unless you spent the day in a cave (that is, a cave without Internet access), you saw how ugly the markets were. The S&P 500Dow Industrials Average, and Nasdaq Composite all will report some of their biggest single-day declines of 2015 once the markets close.

The biggest driver is easily China's ongoing stock market collapse -- which is sure to be referred to as a bubble for years to come -- but continued fears about Greece and Europe are likely playing a role, sending many traders selling in fear and uncertainty. 

But back to WisdomTree. Only a day before, the company's stock was up about 5% -- also on no news -- so it shouldn't be a big surprise to see it down big on a bad day for the markets overall. Furthermore, WisdomTree stock has a pretty high beta of more than 2 -- indicating it has been more than twice as volatile as the index -- another reminder that this has been a stock that moves around quite a bit. 

The bottom line? Without any new material information about the company, there's not really any actionable news to report. In other words, if the stock was on your buy list, you just got a nice discount if you acted today. Congrats!

But if you sold because of the drop, well, that's letting the tail wag the dog...

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.