For hedge fund titan John Paulson, history may be repeating itself.
The billionaire investor lost an estimated $258 million on Tuesday when the share price of drug company Allergan Plc tumbled nearly 15 percent on speculation new tax rules would scuttle its merger with Pfizer Inc..
Research firm Symmetric.io calculated the hypothetical loss based on publicly disclosed stock holdings as of Dec. 31, 2015.
That estimated decline comes after Paulson lost money in late 2014 when his Advantage fund dropped 13.6 percent in October of that year after U.S. pharmaceutical company AbbVie Inc backed out of a planned deal with Irish drug maker Shire Plc after new tax rules made the deal less lucrative for the companies.
Merger-arbitrage specialists such as the $18 billion Paulson & Co bet on the outcome of mergers. Paulson's bet that the Allergan deal would go ahead has been rattled by the new tax rules, which were unveiled on Monday.
Reuters reported on Tuesday that Pfizer was leaning toward abandoning its $160 billion agreement to buy Botox maker Allergan.
Paulson, who made his reputation on bets against the U.S. housing market and said recently in a video interview how critical it was to stay the course in investing, did not comment.
The Paulson Partners fund, which bets on corporate events such as mergers, is down 7.7 percent in 2016 through February, according to a person familiar with the returns. The Paulson Advantage Plus Fund lost 11.24 percent in the first two months of the year. More recent figures were not available.
Paulson is not the only fund that got burned: Symmetric.io estimated that hedge funds in total lost $3 billion on Allergan on Tuesday. Research from Goldman Sachs shows that 80 hedge funds counted Allergan as one of their top 10 holdings at the end of the fourth quarter, making the company one of the most popular stocks in the hedge fund industry.
The pain appears to have been particularly acute for four large hedge fund firms. Viking Global Investors, Paulson & Co, Third Point and Pentwater Capital Management each lost more than $200 million on Tuesday, the Symmetric.io data show, according to year-end holding disclosures.