'Machine' Dalio takes on 'Man' Ackman

Ray Dalio, left, and Bill Ackman
Scott Mlyn | CNBC; Chris Ratcliffe | Bloomberg | Getty Images

It's man versus machine when Bill Ackman meets Ray Dalio.

They are two of the most successful investors in the world, amassing billions of dollars in personal wealth through their hedge fund firms, $18.5 billion Pershing Square Capital Management and $160 billion Bridgewater Associates, respectively.

But their investment and personal styles couldn't be more different.

An activist, Ackman bets on a dozen or fewer companies at once, using his confident, emotional style to try to sway management or other shareholders. Dalio, by contrast, is cautious and mechanistic, relying on huge amounts of data to bet on broad macroeconomic forces and how they move about in 120 markets around the world, from currencies to gold to government bonds.

The disparity was on full display Thursday evening when Ackman interviewed Dalio at the Harbor Investment Conference, a charity event in New York organized by Ackman.

"I'm terrified. I'm a very risk-averse investor," explained Dalio, whose Bridgewater is the largest hedge fund firm in the world.