That works out to a 31.2% return on total average short interest of $973.6 billion throughout the year, according to S3 Partners. Stanphyl Capital portfolio manager Mark Spiegel, who has been short Tesla "constantly, in varying size" since 2014, said a bet against Tesla was his fund's most profitable individual short position this year. While higher interest rates have punished growth stocks, some investors believe Tesla CEO Elon Musk's purchase of Twitter is diverting his time running the electric car company. Long-short hedge funds, which bet on stock prices rising or falling, posted a 9.7% loss through November, according to data provider HFR. Charles Lemonides, portfolio manager at $226 billion hedge fund ValueWorks LLC, believes tight monetary policy will weigh on risk appetite next year.

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