RARE · Ultragenyx Pharmaceutical Inc. · Short Interest
Shares sold short and not yet covered, reported twice monthly. Days to cover is the reported short position divided by average daily volume.
RARE Latest Reported Short Interest
FINRA reported 20,145,283 RARE shares sold short as of the October 15, 2026 settlement date, a decrease of 204,594 shares. Days to cover was 5.18 based on FINRA's reported average daily volume.
Official FINRA short-interest data · share counts are restated for subsequent splits of this listing
RARE Short Interest Forecast
Equibles' model estimates 20,064,911 shares sold short for the October 30, 2026 settlement, -0.4% versus the latest reported position, with a likely range of 18,283,528 to 22,136,653 shares. This model prediction uses FINRA data through October 26, 2026; FINRA's official release is expected November 10, 2026.
Expected Oct 30 short interest
as of Oct 26 Low confidence 51% chance it risesPositioning score 65.8 + catalyst boost 0 (total capped at 100). This is a screening index, not a probability of a squeeze.
Method and coverage limits
Factor percentiles compare eligible primary operating-company stocks reporting short interest at the latest settlement date (2026-10-15). The weighted mean uses short interest 30%, days to cover 20%, price vs VWAP 15%, short-volume trend 15%, short-interest change 10%, and fails-to-deliver 10%. Missing factors redistribute their weight; incomplete coverage is not evidence of low risk. Price, volume, and earnings boosts add 10 each, capped at 20.
Shares outstanding are not free float. Borrow fees, utilization, lendable supply, recalls, and dealer inventory are not measured. Short-sale volume does not measure the change in open shorts; fails to deliver are not a borrow-cost measurement; price vs VWAP does not establish short sellers' entry prices. Earnings can move prices in either direction.
The weights are judgment-based, not calibrated to future squeeze outcomes. The separate options assessment below does not change this universe ranking.
Options positioning & squeeze sensitivity
Nearest expiration after today within 30 calendar days; same-day expirations and later maturities are excluded.
Open interest is incomplete, stale, or dated inconsistently; positioning totals are unavailable.
Open interest has both a buyer and a seller; it does not reveal dealer hedge direction. Gross gamma sums both calls and puts without netting and uses a local 1% price-change approximation. It measures sensitivity, not predicted buying or a squeeze probability.
Assessment prepared 2026-10-27 00:54 UTC. Options model values may come from a cached snapshot; their original computation time is not supplied. Open interest has its own effective date.
Short Interest History
| Settlement Date | Current Position | Previous Position | Change | Days to Cover |
|---|---|---|---|---|
|
2026-11-13
Scheduled
FINRA publishes Nov 24
|
— | — | — | — |
|
2026-10-30
Scheduled
FINRA publishes Nov 10
|
— | — | — | — |
| 2026-10-15 | 20,145,283 | 20,349,877 | -204,594 | 5.18 |
| 2026-09-30 | 20,349,877 | 16,571,956 | +3,777,921 | 3.13 |
| 2026-09-15 | 16,571,956 | 17,144,354 | -572,398 | 2.22 |
| 2026-08-31 | 17,144,354 | 15,887,767 | +1,256,587 | 8.00 |
| 2026-08-14 | 15,887,767 | 14,963,396 | +924,371 | 7.78 |
| 2026-07-31 | 14,963,396 | 13,435,087 | +1,528,309 | 8.28 |
| 2026-07-15 | 13,435,087 | 16,217,153 | -2,782,066 | 6.94 |
| 2026-06-30 | 16,217,153 | 14,312,759 | +1,904,394 | 3.60 |
| 2026-06-15 | 14,312,759 | 14,703,432 | -390,673 | 8.85 |
| 2026-05-29 | 14,703,432 | 13,976,318 | +727,114 | 9.83 |
| 2026-05-15 | 13,976,318 | 13,665,812 | +310,506 | 8.22 |
| 2026-04-30 | 13,665,812 | 12,088,495 | +1,577,317 | 8.40 |
| 2026-04-15 | 12,088,495 | 11,413,679 | +674,816 | 7.09 |
| 2026-03-31 | 11,413,679 | 9,932,072 | +1,481,607 | 4.81 |
| 2026-03-13 | 9,932,072 | 9,597,141 | +334,931 | 4.78 |
| 2026-02-27 | 9,597,141 | 9,861,470 | -264,329 | 5.40 |
| 2026-02-13 | 9,861,470 | 9,095,903 | +765,567 | 3.92 |
| 2026-01-30 | 9,095,903 | 8,861,656 | +234,247 | 3.85 |
| 2026-01-15 | 8,861,656 | 8,017,399 | +844,257 | 2.72 |
| 2025-12-31 | 8,017,399 | 8,600,577 | -583,178 | 1.88 |
| 2025-12-15 | 8,600,577 | 8,871,538 | -270,961 | 5.66 |
| 2025-11-28 | 8,871,538 | 7,828,953 | +1,042,585 | 7.17 |
| 2025-11-14 | 7,828,953 | 7,144,800 | +684,153 | 5.33 |
| 2025-10-31 | 7,144,800 | 8,692,947 | -1,548,147 | 5.63 |
Full FINRA short interest reporting calendar