I found this pretty interesting: Short Interest - Keep an eye on short interest profiles with our new Short Interest tear sheet. Graphs short interest as a percent of float, days short, or shares short, while the short interest log provides exact values on a semi-weekly basis. https://www.interactivebrokers.com/en/?f=/en/software/releaseNotes/tws_notes_949.php#949_futures My impression was that exchanges only report short interest totals per stock to FINRA twice monthly, and FINRA makes that data public with considerable lag. How is Interactive Brokers able to calculate "exact" short interest twice weekly? I imagine they could easily extrapolate daily short interest estimates from their own customer accounts (i.e., compare their customer short positions to FINRA as of their last date reported, and then assume that proportion is maintained daily), but that would not be "exact".