Why They Matter: Ask any MBA student what she wants to be when she grows up, and chances are she'll gush about landing a job at a private-equity firm like Blackstone, Carlyle, Kohlberg Kravis Roberts, or Texas Pacific Group.
And why not? Private-equity shops raised a record $217 billion in new capital in the United States alone during 2006 and are now busy buying up everything from massive REITs like Zell's Equity Office Partners (purchased by Blackstone for $38.3 billion) to tiny startups like visual effects firm the Mill.
With so much private money flowing into every sector of the economy, some foresee a train wreck. Perhaps. But in the meantime, PE firms announced more than a quarter-trillion dollars' worth of deals in the first five months of this year -- which means that, for better or worse, private equity will make its presence felt for a long time to come.