(Adds Box statement)
Sept 3 (Reuters) - U.S. hedge fund Starboard Value LP revealed here a 7.5% stake in cloud service provider Box Inc on Tuesday, calling its shares "undervalued".
Box shares were up about 7% at $15.84 after the bell. Up to Tuesday's close, the stock had fallen 12% this year.
Starboard is now the second-biggest stakeholder in the company after Vanguard Group Inc, which has an 11.41% stake as of June 30, according to Refinitiv data.
In a regulatory filing disclosing its stake, Starboard said it may talk to Box about the company exploring a sale, as well as operational improvements.
Box, in response to Starboard's filing, said it was committed to maintaining an active and engaged dialogue with stockholders.
Last week, Box reported better-than-expected second quarter revenue, but its shares fell 8% in extended trading as investors were disappointed after the company reiterated its full-year earnings outlook. (Reporting by Ayanti Bera in Bengaluru; Editing by Shailesh Kuber)