PACB Dark Pool Activity
Pacific Biosciences of California, Inc.
Data as of Oct 23, 2026 · Source: FINRA daily short sale volume (off-exchange)
On Oct 23, 2026, FINRA reported 2.2M PACB shares in publicly disseminated off-exchange trades (dark pools and other off-exchange venues). 1.0M of those shares (47.2%) were marked short or short-exempt, above PACB's 30-day rolling average of 40.7% (z-score 0.60). Over the last 10 FINRA sessions (Oct 12, 2026 – Oct 23, 2026), PACB's off-exchange short volume ratio ranged from 16.7% to 66.0% and averaged 40.1%; the latest reading is above that 10-session average.
Off-Exchange Volume
2.2M
Short Volume
1.0M
Short Volume Ratio
47.2%
30-Day Average
40.7%
z-score 0.60
Daily readings — last 10 FINRA sessions
| Date | Off-exchange shares | Short shares | Short ratio |
|---|---|---|---|
| Oct 12, 2026 | 5.0M | 1.5M | 29.3% |
| Oct 13, 2026 | 5.2M | 860K | 16.7% |
| Oct 14, 2026 | 3.8M | 818K | 21.5% |
| Oct 15, 2026 | 5.9M | 1.5M | 25.9% |
| Oct 16, 2026 | 4.7M | 2.4M | 51.3% |
| Oct 19, 2026 | 2.6M | 1.2M | 44.5% |
| Oct 20, 2026 | 5.2M | 2.6M | 50.1% |
| Oct 21, 2026 | 6.8M | 4.5M | 66.0% |
| Oct 22, 2026 | 4.1M | 2.0M | 48.6% |
| Oct 23, 2026 Latest | 2.2M | 1.0M | 47.2% |
Source: FINRA daily short sale volume (off-exchange). Ratio = ShortVolume ÷ TotalVolume for the day.
PACB dark pool FAQ
- How much PACB off-exchange volume did FINRA report on Oct 23, 2026?
- FINRA's daily short sale volume file reported 2.2M PACB shares in publicly disseminated off-exchange trades on Oct 23, 2026; 1.0M of those shares (47.2%) were marked short or short-exempt.
- Is PACB's dark pool short volume ratio unusual right now?
- As of Oct 23, 2026, PACB's short volume ratio of 47.2% is above PACB's 30-day rolling average of 40.7% (z-score 0.60). Meridian's dark pool model does not flag this reading as an anomaly.
- What does the dark pool short volume ratio measure?
- FINRA publishes daily short sale volume for trades reported off-exchange to its trade reporting facilities, which include dark pools and other off-exchange venues. The ratio divides FINRA's ShortVolume figure, which counts both short and short-exempt sales, by the total off-exchange shares reported for that day. It is not short interest and not a directional signal: market-maker hedging and reporting mechanics can raise it, so it is context for other signals.