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: Shares of GoPro (NASDAQ:GPRO) had surged by as much as 11% by 2:50 p.m. Tuesday following an analyst upgrade from Northland Securities, which put an outperform rating on the stock and attached a $70 price target. Tuesday also marked the expiration of a lockup period tied to GoPro's initial public offering. At 2:50 p.m., GoPro traded just over $50 per share.

Why It's Happening: Northland Securities' rationale for the upgrade is as follows: "GoPro is demonstrating strong new product momentum with its HERO4 that is driving ASP [average selling price] and GM [gross margin] uplift. We think the company is uniquely positioned to create new niche digital image capture devices that augment camera phones. In addition, the company has strong brand recognition positioning it to benefit from the growth of digital video curation on social media."

This upgrade comes less than two weeks after the stock sank following its fourth-quarter earnings report. Shares of GoPro are down about 50% from the 52-week high reached in October, and analysts are mixed on the stock. JPM Securities maintains the highest price target on the stock at $105, while Oppenheimer has one of the lowest at $35.