ShortInterestHistory.com

UPB Short Interest History

UPB Short Interest (September 15, 2026 Update)
Short interest for UPB was 4.5M as of September 15, 2026, +9.7% from the prior report.
This page tracks UPB short interest over time, including historical values, changes between reports, and days to cover.

Upstream Bio, Inc. Common Stoc | UPB | Nasdaq | Latest report: September 15, 2026

Current Short Interest4.5M
Prior Short Interest4.1M
Change Shares395.7K
Change %+9.7%
Average Daily Volume656.2K
Days to Cover6.84

At the latest settlement date of September 15, 2026, Upstream Bio, Inc. Common Stoc (UPB) showed reported short interest of 4,490,724 shares. That compared with 4,095,011 shares in the prior report, a change of 395.7K shares, or +9.7%. The latest reported days to cover was 6.84, based on average daily volume of 656.2K.

The historical data currently tracked for UPB includes 45 reported entries from October 15, 2024 to September 15, 2026. Over that span, reported short interest has ranged from 230.7K to 4.8M shares.

Short Interest Over Time

Days to Cover Over Time

Extreme edge-case readings may reflect unusually low reported average volume.

Short Interest History for UPB

Settlement DateShort InterestPrior Short InterestChange SharesChange %Average Daily VolumeDays to Cover
September 15, 20264,490,7244,095,011395.7K+9.7%656.2K6.84
August 31, 20264,095,0114,016,61478.4K+1.9%549.5K7.45
August 14, 20264,016,6143,648,558368.1K+10.1%712.4K5.64
July 31, 20263,648,5583,618,15130.4K+0.8%487.0K7.49
July 15, 20263,618,1514,105,630-487.5K-11.9%442.1K8.18
June 30, 20264,105,6303,898,229207.4K+5.3%718.3K5.72
June 15, 20263,898,2293,640,867257.4K+7.1%711.5K5.48
May 29, 20263,640,8673,397,759243.1K+7.2%534.4K6.81
May 15, 20263,397,7593,223,622174.1K+5.4%507.8K6.69
April 30, 20263,223,6223,022,894200.7K+6.6%564.2K5.71
April 15, 20263,022,8943,435,261-412.4K-12.0%576.9K5.24
March 31, 20263,435,2614,752,354-1.3M-27.7%991.8K3.46
March 13, 20264,752,3544,086,377666.0K+16.3%1.1M4.44
February 27, 20264,086,3773,529,797556.6K+15.8%2.2M1.83
February 13, 20263,529,7973,183,884345.9K+10.9%2.3M1.52
January 30, 20263,183,8843,451,544-267.7K-7.8%574.4K5.54
January 15, 20263,451,5443,486,600-35.1K-1.0%652.3K5.29
December 31, 20253,486,6002,983,568503.0K+16.9%606.0K5.75
December 15, 20252,983,5682,773,635209.9K+7.6%534.4K5.58
November 28, 20252,773,6352,994,056-220.4K-7.4%541.3K5.12
November 14, 20252,994,0562,929,47664.6K+2.2%383.3K7.81
October 31, 20252,929,4763,336,913-407.4K-12.2%371.5K7.88
October 15, 20253,336,9133,564,217-227.3K-6.4%324.8K10.27
September 15, 20253,011,6533,097,969-86.3K-2.8%662.7K4.54
August 29, 20253,097,9693,160,080-62.1K-2.0%352.9K8.78
August 15, 20253,160,0803,080,80079.3K+2.6%491.4K6.43
July 31, 20253,080,8003,781,146-700.3K-18.5%536.1K5.75
July 15, 20253,781,1464,109,973-328.8K-8.0%267.7K14.13
June 30, 20254,109,9733,610,360499.6K+13.8%718.7K5.72
June 13, 20253,610,3603,685,383-75.0K-2.0%358.8K10.06
May 30, 20253,685,3833,746,059-60.7K-1.6%386.0K9.55
May 15, 20253,746,0593,940,057-194.0K-4.9%362.9K10.32
April 30, 20253,940,0574,067,418-127.4K-3.1%296.8K13.28
April 15, 20254,067,4183,895,476171.9K+4.4%299.9K13.56
March 31, 20253,895,4763,712,999182.5K+4.9%251.0K15.52
February 28, 20253,702,5883,462,980239.6K+6.9%212.4K17.43
February 14, 20253,462,9802,717,049745.9K+27.5%292.6K11.83
January 31, 20252,717,0492,392,790324.3K+13.6%240.7K11.29
January 15, 20252,392,7902,302,00390.8K+3.9%254.4K9.4
December 31, 20242,302,0031,217,8281.1M+89.0%645.7K3.57
December 13, 20241,217,8281,205,87612.0K+1.0%231.8K5.25
November 29, 20241,205,8761,039,477166.4K+16.0%246.9K4.88
November 15, 20241,039,477647,123392.4K+60.6%241.4K4.31
October 31, 2024647,123230,692416.4K+180.5%343.0K1.89
October 15, 2024230,6920230.7K+100.0%379.1K1

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