Starbucks CEO Kevin Johnson will step down in April and Howard Schultz will return to lead the company for the third time. The move comes as the chain confronts rising costs, challenges in the Chinese and Russian markets, and an expanding unionization push among U.S. baristas. Wall Street analysts said a new CEO could improve investor sentiment toward the stock, which has trailed other restaurant-company shares in recent months. Starbucks shares rose 5.2% Wednesday.