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Paul McCartney may be about to be surpassed as the wealthiest rock musician in the world by U2 frontman Bono.  NME.com reports that the Irish rocker, who owns a 2.3 percent stake in Facebook, is expected to see his net worth increase significantly when the social-networking company goes public on Friday.

Facebook is valued at more than $100 billion, which will make Bono's share worth in excess of $1.5 billion.  In comparison, the Beatles legend's fortune is estimated to be slightly over $1 billion.

Bono bought his Facebook shares for about $90 million back in 2009 through his private equity company Elevation Partners.