We're not exactly crying over the $4.7 billion in net worth Facebook founder Mark Zuckerberg lost over 11 days, but here's one way to measure it: he's no longer one of the 40 richest human beings on the planet, as ranked by the Bloomberg Billionaires Index. The chart above shows his ranking starting at No. 29 in the pantheon of earthly wealth on May 17, the day before Facebook's IPO. His net worth peaked post-IPO at $19.4 billion and so did his ranking, at No. 26. But on Tuesday, after a run of bad news starting with bugs in NASDAQ's computer systempessimistic bankers at Morgan Stanleyand punctured tech bubble, Zuckerberg's net worth, according to Bloomberg, dropped to a mere $14.7 billion, low enough to end his run in their top 40. It was sure nice while it lasted. (He's still very, very rich.)