In the following video, Fool.com contributor John Reeves gives investors his weekly wrap-up, and tells us the story behind three stocks that were really hit hard this week. He discusses InvenSense's (INVN) nearly 20% fall after an analyst downgrade, part of a continuing trend for the company. He also tells us about Westport Innovations' (WPRT 0.67%) 5% fall this week, as the stock for this potentially disruptive natural gas engine company remains volatile on uncertainty about the future of the technology. Then he discusses SandRidge's (NYSE: SD) 9% drop this week, on concerns over both management, and the company's production.