5 of Last Week's Biggest Winners

What's better than momentum? Mo' momentum. Let's take a closer look at five of this past week's biggest scorchers.

Source: Barron's.

Let's start with Celldex Therapeutics. The biotech kicked off the week by announcing a pilot study in treating dense deposit disease, but then the fireworks started when Mad Money's Jim Cramer made bullish comments about the company during Monday night's show. Guggenheim followed, initiating coverage of Celldex with a "buy" rating and a $24 price target.

Novavax surged on encouraging news for a treatment that's still early in the regulatory approval process. Positive top-line safety and immunogenicity data for its promising respiratory syncytial virus vaccine in elderly adults sent the stock higher, but we're still in the first phase of the clinical trials process.

Zynga soared after tapping Xbox boss Don Mattrick as its new CEO. Founder Mark Pincus will stick around as board chairman and chief products Ooficer, but having a prolific new CEO step in is impressive.

Zynga has been a disaster since going public at $10 in late 2011. Executives began bolting last year as the stock price tanked and bookings weakened. Mattrick's arrival won't change that overnight, but the perception of the leading player in social and casual games certainly improves.

Glu Mobile moved 15% higher on the week. The maker of mobile games introduced a new title on Wednesday. Tons of Guns is a free-to-play first-person shooter in which players have to reclaim their armories through a series of battles.

However, clearly Glu's pop doesn't materialize if it wasn't for the news at Zynga. Mattrick's arrival signals validation for the entire niche of social and casual gaming.

Finally, we have Tesla Motors accelerating to yet another all-time high. The darling among electric-car makers impressed investors by announcing that it has received hundreds of orders for its Model S sedan in China, even though the fast-growing automaker has yet to even announce pricing for the vehicle in the world's most populous country.

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