(Corrects to "Vanguard" from "Vangaurd" in paragraph 3)
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 7.1% $15.90 after the bell.
Starboard is now the second biggest stakeholder in the company, after Vanguard Group Inc, which has a 11.41% stake. (Reporting by Ayanti Bera in Bengaluru; Editing by Shailesh Kuber)