John Thain estimates that Merrill Lynch's 20% stake in financial information supplier Bloomberg could be worth up to $6 billion.

The valuation puts a $30 billion price tag on the company and makes Thomson's $8.8 billion buy-out of Reuters seem a positive snip.

It also offers an insight into the personal net worth of the company's eponymous founder. Currently slumming it as the Mayor of New York, Michael Bloomberg still holds a 70% stake in the company he established back in the early 1980s.

With a $21 billion fortune at his disposal, Bloomberg can safely take his place among the ranks of the world's twenty richest people. According to Forbes' 2008 ranking of the world's billionaires, Bloomberg would sit at joint 19th with a wallet big enough to match that of Saudi oil sheikh Prince Alwaleed Bin Talal Alsaud.