George Soros, the billionaire hedge-fund manager who has broken the British pound and some Republican hearts, is betting that the U.S. stock market could break, too.

Soros Fund Management had $1.3 billion worth of options at the end of 2013 that pay off if the Standard & Poor's 500-stock index falls, the Bullion Baron blog reported last week, citing the fund's latest regulatory filing. It was Soros' biggest position, making up 11 percent of his fund's holdings.

The filing is a snapshot of Soros' position at the end of the fourth quarter of 2013. He might have raised or lowered that bet since then. He might also be using the position to hedge some other bet. He's certainly not going to tell us. Closing out the bet would have made some sense in the middle of February, after the S&P had fallen more than 5 percent for the year.

But Soros definitely jacked up the bet going into the end of the year, to $1.3 billion from $470 million in the third quarter. And just last month he warned about risks to the global economy, mainly from China.

Soros is maybe most famous, or infamous, these days for being sort of the liberal version of the Koch Brothers -- a wealthy guy pumping millions into progressive candidates and causes.

But he has also been a fairly savvy investor over the decades, most famously making $1 billion on a successful bet against the British pound in 1992, an event still known as "Black Wednesday" in the U.K..

In case you're thinking of ignoring Soros because of politics or because hedge funds are absolutely the worst at predicting the future, keep in mind that his fund was the best-performing fund in the world last year, according to a ranking LCH Investments.

And after that brief 5 percent swoon in late January-early February, the stock market has bounced right back to its record highs, capping a nearly uninterrupted tear since March 2009. Most terrifyingly, ordinary investors are starting to tiptoe back in -- always a worrisome sign.