.  Shorting stocks has been an exercise in frustration of market bears as the SPDR S &amp; P 500 Trust the biggest exchange-traded fund tracking the broad index,⬆️to $68.1 billion last week, the highest level in data going back to January 2016 @WSJ If you trade #forex via #SPX500👇 https://t.co/vv2UDWcPEv