(Reuters) - Hedge fund Maplelane Capital in December raised its bearish options bets on GameStop Corp and American Airlines Group Inc, companies that were at the heart of a retail investor-led rally in heavily shorted stocks earlier this year. Maplelane also disclosed it had put options on 800,000 shares of Bed Bath & Beyond Inc as of Dec. 31, 2020, a regulatory filing showed on Tuesday. (bit.ly/2Zj3AKP) A put option gives the holder the right to sell an asset at a specified price and is often used as protection against a slide in the market. It can also be used as a way for a hedge fund to short a stock without using equity markets. A retail-trading boom, fueled by online discussion forums such as WallStreetBets, drove volumes in U.S. equity options to a record monthly high in January. Hedge funds were at the center of the market drama fueled by the battle between small traders and big institutions betting against stocks. Maplelane, which has bet against GameStop, lost roughly 45% in January, Reuters had reported, citing a person familiar with the fund"s returns. (reut.rs/3b9fegS) The GameStop surge also resulted in massive losses for Melvin Capital, one of the biggest funds betting on a drop in GameStop’s share price. Melvin lost 53% in January, while other funds like billionaire investor Steven Cohen’s Point72 Asset Management lost nearly 9%. Maplelane disclosed on Tuesday it had put options on 1.6 million Class A GameStop shares at the end of December, compared with 1 million shares in September. On American Airlines, it had put options on 5.5 million shares, compared with 3.2 million shares at the end of September. Shares of GameStop and Bed Bath and Beyond were down about 3% and 1% respectively, while American Airlines’ shares were up 2%.