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's happening: Natural gas engine technology expert Westport Innovations' (NASDAQ:WPRT) stock is down big today -- 14% at last count around 1:10 p.m. EDT. Earlier in the trading day it was down as much as 18%. 

Why it's happening: Westport reported earnings for its fourth quarter and full year 2014 after the market closed on March 9, and was actually up strongly during trading hours before earnings. 

The company reported a bigger loss than Wall Street analysts were expecting, which is at least partly behind today's big sell-off, but even after today's beating the stock is still up almost 50% from its low in mid-January:

WPRT Chart

WPRT data by YCharts.

The big-picture reality for Westport shareholders right now: This stock is likely to be very volatile, as a lot of questions remain about the company's future and its ability to move from cash-burning technology developer to profitable manufacturer. 

Looking for more coverage from Westport's earnings? Go here for my full take.