What's happening: Shares of natural gas engine technology company Westport Innovations (NASDAQ:WPRT) dropped like a rock this morning, falling below 10% at one point, before recovering. As of this writing, it's down around 5%, but that's just another day at the market for Westport this year.

It's been one of the most volatile stocks out there:

WPRT Chart

WPRT data by YCharts.

Why it's happening: There's no material news regarding Westport today, but the U.S. markets are all down following another huge drop in the Chinese stock market. Considering how volatile Westport stock is now, it should be no surprise that it falls more than the overall market when there's relatively bad overall news that's pushing the market lower. Add in that Westport reports earnings in a few days, and there's likely even more short-term trading activity taking place. 

For long-term shareholders, nothing changed today (either good or bad). Just market volatility. Keep an eye out here on July 29 for coverage of Westport's quarterly earnings report.