The U2 frontman bought a 2.3 per cent share in the site for $89.6 million (£56 million) in 2009, with his investment group Elevation Partners, and now the U.K.'s Sunday Mirror reports his share is worth a huge $1.5 billion.

As a result, he overtakes Beatles legend Sir Paul MCCartney - who has a $1.16 billion fortune - as the world's richest pop star.

Facebook.com went public and was floated on the stock market in 2012, and is now worth around $200 billion.