Bets against regional banks continue to pile on even as the sector recovers from the turmoil that shook financial markets in March. Short interest as a percentage of shares outstanding in the SPDR S&P Regional Banking ETF (ticker KRE) rose to 92% from 74% a week ago, according to data compiled by S3 Partners, a technology and data-analytics firm. When accounting for the synthetic long bets created in each short sale, it means almost 48% of positions in the ETF are wagering on a decline, up...