$FBRX

Fails-to-deliver = shares that weren't delivered to settle a trade by the due date. Persistent spikes are a classic short-squeeze / illiquidity tell the degen crowd watches.

source: SEC fails-to-deliver data · free · updated twice monthly (~3–4 wk lag)

source: FINRA OTC Transparency (ATS + non-ATS) · free · weekly, ~2–4 wk lag