Bono told MSNBC's Andrew Mitchell in the US: "In Elevation, we invest other people's money - endowments, pension funds. We do get paid, of course."
But one of the most anticipated IPOs in Wall Street history ended on a flat note, with Facebook's stock closing at $38.23, up 23 cents from the previous day's pricing.
That means the company has a market value of about $105 billion, more than Amazon.com and McDonald's.
It also gave 28-year-old Zuckerberg a stake worth $19,252,698,725.50.
But the increase of six-tenths of one per cent was a letdown.
"I don't think there'll be barroom bragging tonight," said John Fitzgibbon, founder of IPO Scoop, a research firm.
- AAP