Stocks showed mixed results during the two-week period ended April 30. The Dow Jones increased 0.9 percent while the Valley 50 dropped 1.4 percent. Online marketing firm Conversant Inc. (formerly called ValueClick) led as the top gainer at 16 percent, ahead of its annual report release this week. Specialty retailer Sport Chalet Inc. followed with a gain of 11 percent. IPC The Hospitalist Co. Inc. had the biggest drop with 17 percent as the health care company reported earnings per share that stayed flat compared to a year ago. DreamWorks Animation SKG Inc. fell 12 percent based on a poor first quarter that included a $57 million write-down for its spring release, “Mr. Peabody and Sherman.”