TripAdvisor LLC listed on Nasdaq Wednesday, Dec. 21, after being spun off from Expedia Inc. TripAdvisor CEO Stephen Kaufer discusses the company's acquisition strategy, which has recently been in the mobile, social and vacation rental spaces. "They've all turned out to be very good for us," Kaufer says of the purchases. "It's a fair bet to say that, at some level, they will continue in the future." - Katie Roof