Activist investor Starboard Value disclosed a 9% stake in Tripadvisor on Thursday and said the stock was undervalued.

Expedia’s stock ended the holiday-shortened session up 3.2%, its largest rise since it rose 3.8% on May 27. Tripadvisor’s stock shot up 16.7%, and has soared 34.1% over the past three sessions. Among others in the travel-services space, Airbnb Inc.’s stock was up 0.8% and Booking Holdings Inc. shares moved higher by 0.3%, at the closing bell.

Activist investor Starboard Value has taken a 9% stake in Tripadvisor, and shares of the travel review company jumped Thursday.