Sir Paul McCartney has long been considered the wealthiest musician alive.

However, a new report shows that the legendary artist and former Beatle has slipped into second place on the wealthiest music artist list. Who has challenged Sir Paul for the top spot?

International Business Times says Bono. Facebook has been a really good 'friend' for the legendary U2 frontman.

The Irish singer's wealth has increased greatly in recent years thanks to his 2.3-percent ownership of Facebook, a windfall that, according to sources, now is worth about 940 million pounds -- or more than $1.4 billion.

That figure would easily put Bono ahead of Sir Paul, whose fortune was valued at 730 million pounds, or about $1.1 billion, according to the latest annual Sunday Times of London's Rich List. McCartney's figure also includes about $225 million from his wife, trucking heiress Nancy Shevell.

International Business Times points out that the money Bono has made from his share of Facebook, which he purchased in 2009 when the social media website went public, is worth more than all the cash he's earned as a member of U2.