PRTA
Prothena Corporation plc
stockNASDAQ
At CloseNov 13, 2026 3:59:59 PM EST
8.17USD-0.729%(-0.06)340,447
After-hoursNov 13, 2026 4:15:30 PM EST
8.17USD0.000%(-0.00)
As of 2026-10-30, there were 7,911,160 shares short with a short interest of 18.02%.
PRTA Short Interest - Official
PRTA Short Position Change - Official
PRTA Short Interest - Official
| Settlement Date1 | Short Interest % | Short Position | Days to Cover2 | Short Position Change | Short Position Change % | Shares Out | Shares Float |
|---|---|---|---|---|---|---|---|
| 2026-10-30 | 18.02 | 7,911,160 | 15.69 | -28,506 | -0.36 | 51,336,974 | 43,912,232 |
| 2026-10-15 | 18.04 | 7,939,666 | 13.28 | -71,198 | -0.89 | 51,336,974 | 44,022,248 |
| 2026-09-30 | 17.21 | 8,010,864 | 13.79 | -533,800 | -6.25 | 51,336,974 | 46,546,444 |
| 2026-09-15 | 18.36 | 8,544,664 | 26.53 | +48,868 | +0.58 | 51,336,974 | 46,546,444 |
| 2026-08-31 | 18.25 | 8,495,796 | 24.85 | -49,331 | -0.58 | 51,336,974 | 46,546,444 |
| 2026-08-14 | 18.36 | 8,545,127 | 19.56 | +372,689 | +4.56 | 51,336,974 | 46,546,444 |
| 2026-07-31 | 17.69 | 8,172,438 | 13.96 | -24,526 | -0.30 | 52,353,237 | 46,192,903 |
| 2026-07-15 | 17.75 | 8,196,964 | 16.40 | -172,604 | -2.06 | 52,353,237 | 46,192,903 |
| 2026-06-30 | 22.93 | 8,369,568 | 11.02 | +502,711 | +6.39 | 52,353,237 | 36,502,247 |
| 2026-06-15 | 17.08 | 7,866,857 | 15.98 | +769,003 | +10.83 | 52,353,237 | 46,061,758 |
| 2026-05-15 | 16.84 | 7,097,854 | 12.96 | +226,389 | +3.29 | 52,353,237 | 42,136,682 |
| 2026-04-30 | 15.84 | 6,871,465 | 18.33 | -205,367 | -2.90 | 53,832,982 | 43,391,663 |
| 2026-04-15 | 16.31 | 7,076,832 | 15.33 | +60,752 | +0.87 | 53,832,982 | 43,391,663 |
| 2026-03-31 | 16.17 | 7,016,080 | 12.32 | -28,710 | -0.41 | 53,832,982 | 43,391,663 |
| 2026-03-13 | 16.24 | 7,044,790 | 11.20 | +190,023 | +2.77 | 53,832,982 | 43,391,663 |
| 2026-02-27 | 15.80 | 6,854,767 | 17.22 | -228,276 | -3.22 | 53,829,982 | 43,391,663 |
| 2026-02-13 | 16.32 | 7,083,043 | 18.12 | +19,349 | +0.27 | 53,829,982 | 43,391,663 |
| 2026-01-30 | 16.28 | 7,063,694 | 13.90 | -5,777 | -0.08 | 53,829,982 | 43,391,663 |
| 2026-01-15 | 16.29 | 7,069,471 | 14.42 | +484,939 | +7.36 | 53,829,982 | 43,391,663 |
| 2025-12-31 | 15.17 | 6,584,532 | 7.96 | +1,885,406 | +40.12 | 53,829,982 | 43,391,663 |
| 2025-12-15 | 10.83 | 4,699,126 | 6.78 | +59,788 | +1.29 | 53,829,982 | 43,391,663 |
| 2025-11-28 | 10.69 | 4,639,338 | 9.02 | -18,152 | -0.39 | 53,829,982 | 43,391,609 |
| 2025-11-14 | 11.62 | 4,657,490 | 7.38 | +513,375 | +12.39 | 53,829,982 | 40,091,494 |
Historical data is split-adjusted.
1 Data from Finra. Finra publishes an updated file every two weeks.
2 Days to Cover (DTC) is also called Short Ratio. This is the Short Position / Average Daily Trading Volume.