Southeastern Asset Management disclosed in a regulatory filing on Tuesday that it has a stake of nearly 12 percent in Rupert Murdoch's News Corp.
The money management firm said in a filing with the Securities and Exchange Commission that it holds 23,767,700 shares, which is worth about $393 million based on News Corp.'s closing share price of $16.55 on Tuesday.
Following the report, News Corp. shares rose in pre-market trade on Wednesday. (Click here to track the company's stock price.)
(Read more: News Corp. earnings beat, boosted by cable strength)
Southeastern held a 1 percent stake in News Corp. at the end of June, according to Thomson Reuters data.
News Corp., which owns newspapers, including The Wall Street Journal, book publisher HarperCollins, pay-TV assets in Australia and the education company Amplify, recently separated from its entertainment division.
(Read more: Icahnhoists white flag, won't block Dell deal)
Twenty-First Century Fox now operates the film studio and cable and TV properties like Fox News and the broadcast network Fox.
Southeastern and Carl Icahn were involved in a protracted effort that ended on Monday to block Michael Dell's $25 billion offer to take his namesake company private.
—Reuters with CNBC.com