标普500 ETF SPY 空头太多了。About 4.8% of the fund’s shares are now out on loan, the data show. That compares with 2% less than two months ago and 1.7% at the start of the year. While the measure remains well below highs of the last two years -- it rose above 7% more than once in 2020 -- the bearish turn comes at a fragile time in markets.