The filing didn't identify what part of Graham Holdings Berkshire might be interested in buying.
(Read more: Amazon CEO Jeff Bezos buying the Washington Post)
Graham owns Kaplan Education, six television stations, the online magazine Slate and several other ventures.
Berkshire's investment in Graham Holdings is worth roughly $1.1 billion. Berkshire said any deal might involve Graham handing over some of its Berkshire stock along with an unnamed subsidiary.
Berkshire says that if a deal happens, it will benefit both companies.
—By The Associated Press