Here are a few stocks to keep on your radar Friday: 

• MedAssets (NASDAQ:MDAS) shares plunged nearly 30% after the company’s disappointing fourth-quarter earnings report late Thursday, which included a dour projection for fiscal 2011 profit. A slew of investment houses downgraded the stock on Friday.
• Speaking of bad earnings reports, NutriSystem (NASDAQ:NTRI) fell 29.4% on Friday after the company’s fourth-quarter earnings report late Thursday that included news that revenue had fallen nearly 17% from a year earlier. On Friday, both Lazard and Janney Montgomery Scott downgraded the shares.
• Salesforce.com (NYSE:CRM) shares gained 6.2% after beating analysts’ fourth-quarter earnings estimates. That news seemed to offset the company’s mixed guidance for the first quarter and full fiscal year.
• Plastic-shoe retailer Crocs (NASDAQ:CROX) were off 8 cents to $18.01 after the company beat fourth-quarter estimates late Thursday and boosted its forecast for the first quarter. Stifel Nicolaus raised its price target on the stock to $23 from $22.
• SandRidge Energy (NYSE:SD) shares were up nearly 9% after the company said late Thursday that its fourth-quarter loss was narrower than what the Street had expected. The company also said it agreed to sell certain properties in New Mexico for $200 million.