Hillhouse Capital is one of world's biggest and most successful investment firms, a financial powerhouse that has raised billions of dollars from universities, pension funds, foundations in the U.S. and elsewhere and reinvested those funds to produce outsized returns. This week, we look at one of the biggest names in global finance, an Asia-focused firm founded in 2005 by a freshly-minted MBA named Zhang Lei. With $20 million from the endowment at Yale, his alma mater, Zhang returned to China an