Related: Evaluating the Biotech ETF Rally

XBI’s recent bullishness has some bearish traders running for the hills. The ETF is up 7% over the past month and posted a third-quarter gain of over 10%.

“XBI’s solid stretch has had short sellers jumping ship. Short interest decreased by 10% during the last two reporting periods to 24.84 million shares. However, it would take nearly nine days for shorts to cover these remaining bearish bets, at XBI’s average daily trading volume, meaning there’s ample sideline cash to fuel a bigger rally,” according to Schaeffer’s.

For more information on the biotech sector, visit our biotechnology category.