THE short-vol trade is dead. Long live the short-vol trade. Investors are discovering fresh ways to bet volatility across asset classes will tumble anew even as hawkish monetary policy, emerging-market turmoil and February's vol-mageddon underscore headwinds to the complex trade. Hedge funds hold the most number of short positions on the Cboe Volatility Index since late January. And they're now punting on a slew of hot derivatives trades across global equity and debt markets.