Traders are making a big change to how they use the world's hottest investment product

Getty Images Some investors use exchange-traded funds to achieve easy portfolio diversification. Others are attracted to their relatively low fees. But what they're not doing is using ETFs to bet on share declines. At least not lately. Short interest currently sits at 6.1% of total ETF assets, the lowest level since the financial crisis, according to data compiled by JPMorgan. That comes amid a roughly 30% drop in total short interest for US-listed funds over the past seven months. The measure n...