Billionaire hedge fund manager David Einhorn just ended his worst year ever.

His Greenlight Capital's main fund lost 9 percent in December, bringing its decline for 2018 to 34 percent, the worst performance since Einhorn started the firm in 1996, according to figures obtained by CNBC's Scott Wapner.

This collapse came in a dismal year when stocks and other risk assets took a huge hit from the ongoing trade battles and slowing global growth. However, Einhorn's hedge funds underperformed the market drastically — the S&P 500 ended 2018 down just 7 percent.

Greenlight's largest holdings include General Motors, insurer Brighthouse Financial and homebuilder Green Brick Partners, which all struggled in 2018, bleeding as much as 47 percent.

2018 sharply contrasted Einhorn's early years, when he scored some of Wall Street's best returns including 24 percent in 2006 and 32 percent in 2009. Einhorn also called the collapse of Lehman Brothers, perhaps the most prescient call of the entire financial crisis. He confirmed he was short Lehman a few months before the firm declared bankruptcy.

When it comes to losing money, Einhorn wasn't shy about expressing his frustration. In a letter to investors in July, he said "over the past three years, our results have been far worse than we could have imagined, and it's been a bull market to boot."

"Yes, we have made some obvious mistakes — the worst of which was not assessing that SunEdison was a fraud in 2015 — but there have been others. A number of years ago one of our investors said Amazon would surpass Apple and become the most valuable company in the world. We didn't get it then and, truthfully, we don't really get it now," he said in the July letter.

His funds have been lackluster since 2015 when they lost more than 20 percent. They returned 7 percent in 2016 and 1.5 percent in 2017.

The hedge fund manager recently became a critic and short seller of Tesla, even comparing the electric car maker to his call on Lehman Brothers.

— CNBC's Scott Wapner contributed reporting.

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