TripAdvisor is expected to grow as activist investors increase pressure on the travel booking company to adopt a more fluid strategy to spur growth, according to Bank of America's research arm. The bank upgraded TripAdvisor to buy from neutral and increased its 12-month price target on the stock to $15 from $14. The move comes after activist investor Starboard Value took a 9% stake in Tripadvisor in July and added four of its members to the board. The company's faster-growing businesses, Viator and TheFork, could be worth a combined $2.5 billion or more.