Short interest tied to major ETFs SPY and QQQ has plummeted to record lows, leaving US equities vulnerable to negative reversals. JPMorgan warns that the vanishing short-sellers have contributed to the relentless rally in stocks, but this trend may pose risks if bad news hits, as there are fewer buyers left in the market. Short interest in S&P 500 members is also at historic lows, according to Goldman Sachs, with assets in funds with a short bias significantly decreasing over the years.