Bloomberg Blooms; Forbes Wilts

(MoneyWatch)  Merrill Lynch's sale of its 20 percent stake in Bloomberg for $4.5 billion -- in a widely leaked deal expected to be announced Thursday -- places a value of $22.5 billion or more on the New York Mayor's privately held firm.

The Times notes that Michael Bloomberg could well be worth more than five times Merrill's holding because Merrill is a distressed seller whose CEO said Merrill's shares were worth more like $5 billion to $6 billion. (Of course, it's probably wise to take Merrill's ability to value assets these days with a grain of salt -- that's why it's in distress, after all.)

If the company is worth $22.5 billion, that means the mayor is worth $16.2 billion -- just in Bloomberg shares -- plus whatever else he holds. Good news for Mayor Mike.

But it's a bit of a black eye for Forbes and its Forbes 400, a list that is the cornerstone of Forbes as a magazine and publishing company. Forbes puts Bloomberg's net worth at $11.5 billion, making him the 25th richest American. If he is really worth $16.2 billion, he'd jump into 16th place, ahead of Steve Ballmer and just behind a flock of Walton heirs (assuming the magazine is right about the others' fortunes). He'd also be perhaps the richest New Yorker, vying with oil and gas billionaire David Koch, who just gave $100 million to Lincoln Center.

So if Forbes is off by 41 percent or more for one of the most visible billionaires in the world, how can anyone believe its numbers are remotely accurate? Good thing no one should care. Knowing how a man makes money may be useful. Knowing how much he's got is gossip.