Upstream Bio, Inc. Common Stoc | UPB | Nasdaq | Latest report: February 27, 2026
At the latest settlement date of February 27, 2026, Upstream Bio, Inc. Common Stoc (UPB) showed reported short interest of 4,086,377 shares. That compared with 3,529,797 shares in the prior report, a change of 556.6K shares, or +15.8%. The latest reported days to cover was 1.83, based on average daily volume of 2.2M.
This page tracks 32 reported short interest entries for UPB from October 15, 2024 through February 27, 2026. Over that period, reported short interest ranged from 230.7K to 4.1M shares.
Reported short interest can change for many reasons, including shifts in sentiment, trading activity, and company-specific events.
Extreme edge-case readings may reflect unusually low reported average volume.
| Settlement Date | Short Interest | Prior Short Interest | Change Shares | Change % | Average Daily Volume | Days to Cover |
|---|---|---|---|---|---|---|
| February 27, 2026 | 4,086,377 | 3,529,797 | 556.6K | +15.8% | 2.2M | 1.83 |
| February 13, 2026 | 3,529,797 | 3,183,884 | 345.9K | +10.9% | 2.3M | 1.52 |
| January 30, 2026 | 3,183,884 | 3,451,544 | -267.7K | -7.8% | 574.4K | 5.54 |
| January 15, 2026 | 3,451,544 | 3,486,600 | -35.1K | -1.0% | 652.3K | 5.29 |
| December 31, 2025 | 3,486,600 | 2,983,568 | 503.0K | +16.9% | 606.0K | 5.75 |
| December 15, 2025 | 2,983,568 | 2,773,635 | 209.9K | +7.6% | 534.4K | 5.58 |
| November 28, 2025 | 2,773,635 | 2,994,056 | -220.4K | -7.4% | 541.3K | 5.12 |
| November 14, 2025 | 2,994,056 | 2,929,476 | 64.6K | +2.2% | 383.3K | 7.81 |
| October 31, 2025 | 2,929,476 | 3,336,913 | -407.4K | -12.2% | 371.5K | 7.88 |
| October 15, 2025 | 3,336,913 | 3,564,217 | -227.3K | -6.4% | 324.8K | 10.27 |
| September 15, 2025 | 3,011,653 | 3,097,969 | -86.3K | -2.8% | 662.7K | 4.54 |
| August 29, 2025 | 3,097,969 | 3,160,080 | -62.1K | -2.0% | 352.9K | 8.78 |
| August 15, 2025 | 3,160,080 | 3,080,800 | 79.3K | +2.6% | 491.4K | 6.43 |
| July 31, 2025 | 3,080,800 | 3,781,146 | -700.3K | -18.5% | 536.1K | 5.75 |
| July 15, 2025 | 3,781,146 | 4,109,973 | -328.8K | -8.0% | 267.7K | 14.13 |
| June 30, 2025 | 4,109,973 | 3,610,360 | 499.6K | +13.8% | 718.7K | 5.72 |
| June 13, 2025 | 3,610,360 | 3,685,383 | -75.0K | -2.0% | 358.8K | 10.06 |
| May 30, 2025 | 3,685,383 | 3,746,059 | -60.7K | -1.6% | 386.0K | 9.55 |
| May 15, 2025 | 3,746,059 | 3,940,057 | -194.0K | -4.9% | 362.9K | 10.32 |
| April 30, 2025 | 3,940,057 | 4,067,418 | -127.4K | -3.1% | 296.8K | 13.28 |
| April 15, 2025 | 4,067,418 | 3,895,476 | 171.9K | +4.4% | 299.9K | 13.56 |
| March 31, 2025 | 3,895,476 | 3,712,999 | 182.5K | +4.9% | 251.0K | 15.52 |
| February 28, 2025 | 3,702,588 | 3,462,980 | 239.6K | +6.9% | 212.4K | 17.43 |
| February 14, 2025 | 3,462,980 | 2,717,049 | 745.9K | +27.4% | 292.6K | 11.83 |
| January 31, 2025 | 2,717,049 | 2,392,790 | 324.3K | +13.6% | 240.7K | 11.29 |
| January 15, 2025 | 2,392,790 | 2,302,003 | 90.8K | +3.9% | 254.4K | 9.4 |
| December 31, 2024 | 2,302,003 | 1,217,828 | 1.1M | +89.0% | 645.7K | 3.57 |
| December 13, 2024 | 1,217,828 | 1,205,876 | 12.0K | +1.0% | 231.8K | 5.25 |
| November 29, 2024 | 1,205,876 | 1,039,477 | 166.4K | +16.0% | 246.9K | 4.88 |
| November 15, 2024 | 1,039,477 | 647,123 | 392.4K | +60.6% | 241.4K | 4.31 |
| October 31, 2024 | 647,123 | 230,692 | 416.4K | +180.5% | 343.0K | 1.89 |
| October 15, 2024 | 230,692 | 0 | 230.7K | +100.0% | 379.1K | 1 |