This indicator combines all the short sale volumes from NASDAQ, NYSE and BATS exchanges and calculates Short Vol % to Total Volume across these 3 exchanges. Use it on Daily Timeframe as shown in the above chart.
When short sale volume data is rising rapidly, it indicates bullishness in the underlying as market makers do not have the shares to sell which results in short sale
When a stock gets dumped by institutions, short sale %age is normally very low and trend is downwards