If you want to limit losses but do not want to sell your holdings, you can buy protective puts. These are options contracts that give you the right to sell the underlying stock or index at a specified price. You can set that specified price at some level below the current market, below which you want to be stopped out for losses (e.g., 10% below the current price). Buying options does incur some cost, so think of it as buying insurance on your portfolio.