"It's one of the best things you can do with your money, legally," said Rubenstein about the top quartile of private equity returns, which he estimates can beat public market returns by as much as nine times. Pension funds that serve the retirement accounts of millions of U.S. workers, for instance, look to high returning private equity investments as a way to manage those future liabilities. In 2011 earnings released on Thursday, the Blackstone Group ( BX ) reported continued inflows of private equity fund assets, in large part by investors like state pension funds and endowments seeking outsized returns not available on Wall Street. Private equity "is not only an important contributor to a healthy economy, it is a vital one," said Blackstone President Tony James on a media call after earnings were released. Blackstone reported a 12% fall in fourth quarter profits on Thursday as fees and income on investments declined in the quarter.