Elevation Partners, a private equity group that counts U2's Bono as co-founder and partner, has bought a stake in family-owned US publisher Forbes.

Elevation Partners has became the first outsider to invest in the company, taking a minority stake in Forbes Media LLC, a new company encompassing the 89-year-old business glossy Forbes magazine, the Forbes.com website and other assets.

The terms of the deal were not disclosed, but reports said the stake was worth about €194 million ($250m).

Elevation Partners is a €1.47 billion ($1.9bn) private equity firm that focuses on media, entertainment and consumer-related businesses.

Aside from Bono, its six partners are Fred Anderson, former chief financial officer of Apple Computers, former Electronic Arts president John Riccitiello and four venture capitalists.

CEO of the publishing firm, Steve Forbes, said that Elevation Partners would help Forbes invest in new strategies in a vastly changed industry where a growing number of readers seek their news via the Internet and other channels.