The maximum gain for a short token position is the amount you sell the token for. The maximum loss is unlimited, as the price of a token can rise forever. Note that these payoffs are the inverse of a long token position. For example, Alice can borrow JAG tokens for $100, and sell it in the market. If the price falls to $90, Alice can buy it back, return the tokens to the person she borrowed them from whilst banking $10 in profit.