Mr Einhorn and Mr Ackman have already made their billions. Losing now has little personal financial impact. Impact is more on the ego today. https://www.cnbc.com/2018/01/18/rising-hedge-fund-stars-are-crushing-the-market.html Einhorn's Greenlight Capital fund returned a meager 1.6 percent in 2017, according to an investor letter. And Ackman's Pershing Square declined 4 percent last year, according to its website. Part of the reason may be the rise of computerized trading. The quantitative-oriented funds could be taking the low-hanging, numbers-based valuation opportunities away. Einhorn tried to explain that his fund's current underperformance was due to a temporary phase in the stock market. "Despite it being a good year in the market, it was a challenging environment for our investment style," he wrote in a note to clients Tuesday. "We have a value orientation and we take comfort from the margin of safety afforded by the low valuations of our long investments … while we certainly don't believe value investing is dead, it is clearly out of favor at the moment."