It's the end of an era. On Dec. 29, Andrew Green, one of the best mutual fund managers of the past two decades, finally closed his funds to new money. London-based Green, who works for UBS' ( UBS) Global Asset Management division, decided that $8 billion was about as much as he could handle if he wanted to continue to beat the market. It's something worth thinking about here in the U.S., where greedy fund management companies continue to put their own interests before those of their investors and let successful funds bloat with new money to $30 billion, $40 billion or even more. Green's success since launching his flagship International Growth (now Global Diversified) fund in January 1984 is something to write home about. Annual returns have averaged 15.2% over that period -- fully a third better than the MSCI index of the world stock markets he invests in. Over 23 years he's turned a $10,000 investment into about $360,000 -- compared to just $95,300 for his benchmark. OK, this figure is boosted by the falling dollar. But even at constant exchange rates, it would come to $260,000. The figure for the Standard & Poor's index over the same period? Just $85,000. No wonder so many investors were prepared to pay a 5% front load, plus 1.5% in fees a year, to get on board. How does he do it?