Short interest in S&P 500 stocks hits highest level since 2011 as hedge funds pile into bearish bets, even as the index keeps hitting all-time highs.

Short interest in S&P 500 stocks hits highest level since 2011 as hedge funds pile into bearish bets, even as the index keeps hitting all-time highs.

S&P 500 short interest nears 15-year highs. Experts warn "conditions for a short-squeeze are rising" as bearish bets surge.