Activist investor Carl Icahn got his start on Wall Street back in 1961. But it was not until the late 1970s that he started his forays into corporate takeovers and hostile bids.

Yes, it has been a great way to build tremendous wealth. Keep in mind that Icahn is now worth more than $12 billion. And despite being 75 years old, he continues to rack up the returns.

In fact, last week, Icahn posted a whopping $535 million gain. A big part of this came from his stake in Motorola Mobility Holdings (NYSE:MMI), which got a big-time buyout offer from Google (NASDAQ:GOOG).

But something else was interesting — that is, Icahn shorted the S&P 500 (according to a report from Bloomberg). It was not necessarily meant to make a gain. Rather, the strategy was an attempt to protect his overall portfolio. But sometimes a hedge can turn into a nice investment.

So with the markets now trading at lower valuations, Icahn certainly is in a nice position. With huge amounts of cash — and borrowing power — he can continue his corporate activism.

And what might be the targets? Well, Icahn has major stakes in companies like Forest Laboratories (NYSE:FRX), Clorox (NYSE:CLX) and Mentor Graphics (NASDAQ:MENT). True, they are not necessarily exciting stocks — but I’m sure Icahn will find a way to make money from them.

Tom Taulli is the author of various books, including “All About Commodities.” He does not own a position in any of the stocks named here.