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Rhythm Pharmaceuticals, Inc.

RYTM
Exchange
Nasdaq
Industry
Pharmaceutical Preparations
SEC CIK
0001649904

In the last 90 days, Rhythm Pharmaceuticals, Inc. insiders filed 0 open-market purchases and 6 sales; 307 institutions reported holding it in 13F filings for Q2 2026, worth $8.55B in total; Duquesne Family Office is the only superinvestor holding it.

Four kinds of short-selling data, each measuring something different:

  • Short interest: shares sold short and not yet bought back, as of a settlement date. FINRA publishes it twice a month, about eight business days after the settlement date.
  • Daily short volume: shares sold short each day in off-exchange trades reported to FINRA. It counts trades, not open positions, and is published the next day.
  • Fails-to-deliver: shares not delivered by the settlement date. The SEC publishes them twice a month, about two weeks late.
  • ATS (dark pool) volume: weekly volume on alternative trading systems and other off-exchange venues. FINRA publishes it two to four weeks after the week.

More in the glossary.

Short interest

Shares sold short and not yet bought back, from FINRA, on every settlement date in the last two years.

Short interest
11.0M
Shares, settlement Oct 15, 2026
Change
+235.8K
+2.2% vs. Sep 30, 2026
Days to cover
13.48
Short interest ÷ average daily volume
Average daily volume
816.3K
Shares, as reported by FINRA
Short interest by settlement date
Oct 15, 2024: 8,460,312 sharesOct 31, 2024: 8,360,239 sharesNov 15, 2024: 6,710,030 sharesNov 29, 2024: 6,367,381 sharesDec 13, 2024: 5,809,632 sharesDec 31, 2024: 5,265,779 sharesJan 15, 2025: 5,453,889 sharesJan 31, 2025: 5,127,767 sharesFeb 14, 2025: 5,410,357 sharesFeb 28, 2025: 5,145,240 sharesMar 14, 2025: 4,710,022 sharesMar 31, 2025: 4,656,313 sharesApr 15, 2025: 5,108,787 sharesApr 30, 2025: 4,852,888 sharesMay 15, 2025: 5,070,846 sharesMay 30, 2025: 4,775,505 sharesJun 13, 2025: 4,757,385 sharesJun 30, 2025: 4,853,861 sharesJul 15, 2025: 4,789,385 sharesJul 31, 2025: 4,514,524 sharesAug 15, 2025: 4,674,524 sharesAug 29, 2025: 4,969,794 sharesSep 15, 2025: 5,220,961 sharesSep 30, 2025: 5,578,461 sharesOct 15, 2025: 5,574,246 sharesOct 31, 2025: 5,230,596 sharesNov 14, 2025: 5,502,046 sharesNov 28, 2025: 5,518,605 sharesDec 15, 2025: 5,581,124 sharesDec 31, 2025: 6,200,378 sharesJan 15, 2026: 6,285,002 sharesJan 30, 2026: 6,237,463 sharesFeb 13, 2026: 6,022,578 sharesFeb 27, 2026: 6,321,762 sharesMar 13, 2026: 6,535,847 sharesMar 31, 2026: 7,624,913 sharesApr 15, 2026: 7,830,912 sharesApr 30, 2026: 8,057,652 sharesMay 15, 2026: 8,282,367 sharesMay 29, 2026: 7,911,004 sharesJun 15, 2026: 8,005,303 sharesJun 30, 2026: 9,665,089 sharesJul 15, 2026: 9,574,527 sharesJul 31, 2026: 9,440,417 sharesAug 14, 2026: 10,154,327 sharesAug 31, 2026: 10,303,031 sharesSep 15, 2026: 10,287,811 sharesSep 30, 2026: 10,767,698 sharesOct 15, 2026: 11,003,490 shares
Short interest in RYTM by settlement date
Settlement dateShort interestChangeChange %Avg. daily volumeDays to cover
Oct 15, 202611.0M+235.8K+2.2%816.3K13.48
Sep 30, 202610.8M+479.9K+4.7%761.7K14.14
Sep 15, 202610.3M−15.2K−0.2%512.8K20.06
Aug 31, 202610.3M+148.7K+1.5%470.7K21.89
Aug 14, 202610.2M+713.9K+7.6%829.8K12.24
Jul 31, 20269.44M−134.1K−1.4%583.7K16.17
Jul 15, 20269.57M−90.6K−0.9%697.0K13.74
Jun 30, 20269.67M+1.66M+20.7%1.28M7.57
Jun 15, 20268.01M+94.3K+1.2%691.4K11.58
May 29, 20267.91M−371.4K−4.5%535.4K14.78
May 15, 20268.28M+224.7K+2.8%1.00M8.28
Apr 30, 20268.06M+226.7K+2.9%553.9K14.55
Apr 15, 20267.83M+206.0K+2.7%611.3K12.81
Mar 31, 20267.62M+1.09M+16.7%1.28M5.93
Mar 13, 20266.54M+214.1K+3.4%861.1K7.59
Feb 27, 20266.32M+299.2K+5.0%694.4K9.10
Feb 13, 20266.02M−214.9K−3.5%762.5K7.90
Jan 30, 20266.24M−47.5K−0.8%528.8K11.80
Jan 15, 20266.29M+84.6K+1.4%636.9K9.87
Dec 31, 20256.20M+619.3K+11.1%771.4K8.04
Dec 15, 20255.58M+62.5K+1.1%1.12M4.98
Nov 28, 20255.52M+16.6K+0.3%647.3K8.53
Nov 14, 20255.50M+271.4K+5.2%785.6K7.00
Oct 31, 20255.23M−343.6K−6.2%566.0K9.24
Oct 15, 20255.57M−4.21K−0.1%528.1K10.56
Sep 30, 20255.58M+357.5K+6.9%712.7K7.83
Sep 15, 20255.22M+251.2K+5.1%609.1K8.57
Aug 29, 20254.97M+295.3K+6.3%507.2K9.80
Aug 15, 20254.67M+160.0K+3.5%627.4K7.45
Jul 31, 20254.51M−274.9K−5.7%545.8K8.27
Jul 15, 20254.79M−64.5K−1.3%1.37M3.48
Jun 30, 20254.85M+96.5K+2.0%569.4K8.53
Jun 13, 20254.76M−18.1K−0.4%588.7K8.08
May 30, 20254.78M−295.3K−5.8%516.2K9.25
May 15, 20255.07M+218.0K+4.5%727.4K6.97
Apr 30, 20254.85M−255.9K−5.0%636.1K7.63
Apr 15, 20255.11M+452.5K+9.7%1.23M4.14
Mar 31, 20254.66M−53.7K−1.1%523.0K8.90
Mar 14, 20254.71M−435.2K−8.5%561.6K8.39
Feb 28, 20255.15M−265.1K−4.9%568.3K9.05
Feb 14, 20255.41M+282.6K+5.5%399.3K13.55
Jan 31, 20255.13M−326.1K−6.0%471.6K10.87
Jan 15, 20255.45M+188.1K+3.6%550.2K9.91
Dec 31, 20245.27M−543.9K−9.4%583.5K9.02
Dec 13, 20245.81M−557.7K−8.8%470.1K12.36
Nov 29, 20246.37M−342.6K−5.1%522.5K12.19
Nov 15, 20246.71M−1.65M−19.7%930.3K7.21
Oct 31, 20248.36M−100.1K−1.2%311.3K26.85
Oct 15, 20248.46M+225.4K+2.7%300.4K28.16

Fails-to-deliver

Shares that weren't delivered by the settlement date, from the SEC, for the last 30 dates with fails. The price is the previous day's closing price published by the SEC.

Fails-to-deliver in RYTM by settlement date
Settlement dateSharesPriceValue
Oct 7, 2026997$90.77$90.5K
Oct 5, 202617,169$92.83$1.59M
Sep 30, 202643$95.71$4.12K
Sep 23, 20262$99.27$198.54
Aug 26, 20263,997$113.35$453.1K
Aug 6, 202612,142$110.71$1.34M
Aug 5, 202644,084$105.78$4.66M
Jul 31, 202611,125$105.74$1.18M
Jul 30, 202668$106.53$7.24K
Jul 22, 2026527$106.60$56.2K
Jul 17, 2026328$106.09$34.8K
Jul 14, 20264$107.49$429.96
Jun 29, 202622,261$109.84$2.45M
Jun 24, 2026160$106.19$17.0K
Jun 22, 20269$96.79$871.11
Jun 18, 202623$95.83$2.20K
Jun 16, 2026242$89.70$21.7K
Jun 15, 202623$88.38$2.03K
Jun 12, 20266$87.66$525.96
Jun 9, 202617$85.93$1.46K
Jun 8, 20262,985$86.40$257.9K
Jun 3, 202613$84.35$1.10K
Jun 2, 202613$87.87$1.14K
May 27, 202613$89.82$1.17K
May 22, 20265$90.19$450.95
May 21, 202611$90.64$997.04
May 18, 2026233$90.52$21.1K
May 14, 202615$93.72$1.41K
May 12, 20269,222$87.39$805.9K
May 11, 202635$94.17$3.30K

Daily short volume

Off-exchange short-sale volume, not short interest: shares sold short each day in trades reported to FINRA, for the last 30 trading days.

The short volume ratio isn't a sentiment gauge: market makers sell short to fill buy orders and to hedge, so short sales are usually about half of off-exchange volume.

Off-exchange short volume in RYTM by trade date
Trade dateShort volumeShort exemptOff-exchange volumeShort volume ratio
Nov 9, 2026265,432207525,71350.5%
Nov 6, 20261,312,9924,8382,795,84447.0%
Nov 5, 20261,587,4833,4122,607,13960.9%
Nov 4, 2026908,20510,5911,815,06050.0%
Nov 3, 20262,544,70417,2693,719,62668.4%
Nov 2, 2026668,6280889,05275.2%
Oct 30, 202697,4370138,86870.2%
Oct 29, 2026204,049149319,65063.8%
Oct 28, 2026154,0680264,85358.2%
Oct 27, 202697,192296141,49968.7%
Oct 26, 202649,9170110,78745.1%
Oct 23, 2026128,1940214,41459.8%
Oct 22, 202698,7500190,34651.9%
Oct 21, 2026173,8381233,32274.5%
Oct 20, 2026373,8530444,07884.2%
Oct 19, 202684,2390134,26762.7%
Oct 16, 202697,7912136,29871.7%
Oct 15, 202699,2700159,53362.2%
Oct 14, 2026120,5350218,40955.2%
Oct 13, 2026203,0121,622280,37972.4%
Oct 12, 202671,93940162,49044.3%
Oct 9, 2026606,9000803,61675.5%
Oct 8, 2026158,3540406,83238.9%
Oct 7, 202697,3480241,50840.3%
Oct 6, 2026314,8010446,19670.6%
Oct 5, 2026133,7020439,09930.4%
Oct 2, 202691,4490168,93254.1%
Oct 1, 202696,65032211,34845.7%
Sep 30, 2026156,8220223,47170.2%
Sep 29, 2026191,2450293,73465.1%

ATS (dark pool) volume

Weekly volume on alternative trading systems (ATS) and other off-exchange (OTC) venues, from FINRA, for the last 12 weeks. ATS share is ATS volume ÷ (ATS + OTC volume), not a share of all trading.

Weekly ATS and OTC volume in RYTM
Week ofTierATS sharesATS tradesOther OTC sharesOther OTC tradesATS share
Oct 5, 2026T22,075,70037,144819,0397,08771.7%
Sep 28, 2026T21,084,09529,195708,5456,48460.5%
Sep 21, 2026T21,379,56025,424253,2815,85384.5%
Sep 14, 2026T21,388,13227,037718,2196,66065.9%
Sep 7, 2026T2671,43524,160198,4654,23477.2%
Aug 31, 2026T2584,21026,292345,3155,41162.9%
Aug 24, 2026T2580,55222,378246,1854,29870.2%
Aug 17, 2026T2902,11830,797287,7464,83075.8%
Aug 10, 2026T2871,48524,311322,0415,46973.0%
Aug 3, 2026T21,882,81534,234821,4956,96169.6%
Jul 27, 2026T21,104,23924,178604,7154,75464.6%
Jul 20, 2026T2791,69427,434338,3673,95870.1%