Alnylam Pharmaceuticals, Inc. short interest
6.6M shares of Alnylam Pharmaceuticals were sold short at the 15 October 2026 settlement, near the middle of its range over the last year (3.8M to 7.7M). Short sellers would need 5.1 days of normal trading to buy them back.
Shares sold short6.6Mat 15 Oct 2026
Change on the settlement before-14.8%+64% over a year
Days to cover5.10at 1.3M shares a day
Of shares in issue4.91%shares short over shares outstanding
New to this? How to read this page
- Short interest is the number of shares investors have borrowed and sold, betting the price will fall, and not yet bought back.
- Days to cover is shares short over an average day's trading: how many days it would take short sellers to buy them all back. Above 5 or so is high.
- Rising short interest says more investors are betting against the stock. A crowded short can also rise fast if shorts rush to buy back.
- Brokers report it twice a month to FINRA, about ten days after each settlement date.
- What is short interest?
Short interest, days to cover and the price
Short interest is near the middle of its range over the last year (3.8M to 7.7M), and the share price moved -52% over the last year.
Shares sold shortDays to coverShare price
Three charts on one timeline. Top: shares sold short at each settlement. Middle: days to cover, taller meaning shorts would need longer to buy back. Bottom: the share price, so you can see whether shorts added as the price fell or rose.
How it compares
every company on the siteThe bar ranks every company on the site from the lowest on the left to the highest on the right, in three equal thirds; the small figures under it are the values where each third starts, and the black tick is the middle company. The orange dot is this company; the grey ticks are the other companies in its industry (hover or tap for names). A hatched block is companies tied at none.
Every settlement since 29 Dec 2017 as a table
| Settlement | Shares short | Change | Average daily volume | Days to cover |
|---|---|---|---|---|
| 15 October 2026 | 6.6M | -14.8% | 1.3M | 5.10 |
| 30 September 2026 | 7.7M | +7.2% | 1.2M | 6.45 |
| 15 September 2026 | 7.2M | +13.5% | 1.7M | 4.13 |
| 31 August 2026 | 6.3M | +32.9% | 1.6M | 3.90 |
| 14 August 2026 | 4.8M | -0.7% | 2.0M | 2.36 |
| 31 July 2026 | 4.8M | -16.8% | 2.2M | 2.18 |
| 15 July 2026 | 5.8M | -0.5% | 1.8M | 3.24 |
| 30 June 2026 | 5.8M | +6.7% | 1.4M | 4.22 |
| 15 June 2026 | 5.4M | +2.6% | 1.1M | 4.76 |
| 29 May 2026 | 5.3M | -1.8% | 918K | 5.78 |
| 15 May 2026 | 5.4M | +13.1% | 1.1M | 5.13 |
| 30 April 2026 | 4.8M | -5.2% | 1.2M | 4.02 |
| 15 April 2026 | 5.0M | -0.4% | 984K | 5.12 |
| 31 March 2026 | 5.1M | +15.7% | 1.3M | 4.01 |
| 13 March 2026 | 4.4M | -4.4% | 1.0M | 4.18 |
| 27 February 2026 | 4.6M | -12.8% | 1.0M | 4.46 |
| 13 February 2026 | 5.2M | -0.7% | 1.9M | 2.80 |
| 30 January 2026 | 5.3M | -5.1% | 1.4M | 3.66 |
| 15 January 2026 | 5.6M | +0.6% | 1.5M | 3.72 |
| 31 December 2025 | 5.5M | +32.2% | 1.9M | 2.89 |
| 15 December 2025 | 4.2M | +5.7% | 1.3M | 3.19 |
| 28 November 2025 | 4.0M | -7.5% | 969K | 4.09 |
| 14 November 2025 | 4.3M | +13.5% | 954K | 4.49 |
| 31 October 2025 | 3.8M | -5.6% | 1.1M | 3.34 |
| 15 October 2025 | 4.0M | +13.9% | 1.1M | 3.48 |
| 30 September 2025 | 3.5M | -5.7% | 1.0M | 3.36 |
| 15 September 2025 | 3.7M | -6.4% | 1.2M | 3.05 |
| 29 August 2025 | 4.0M | +16.0% | 1.1M | 3.73 |
| 15 August 2025 | 3.4M | +5.8% | 1.3M | 2.57 |
| 31 July 2025 | 3.2M | -4.2% | 1.2M | 2.78 |
| 15 July 2025 | 3.4M | +1.6% | 895K | 3.78 |
| 30 June 2025 | 3.3M | -1.4% | 914K | 3.64 |
| 13 June 2025 | 3.4M | -2.1% | 734K | 4.60 |
| 30 May 2025 | 3.4M | -6.3% | 1.1M | 3.23 |
| 15 May 2025 | 3.7M | +16.9% | 1.1M | 3.38 |
| 30 April 2025 | 3.1M | +2.9% | 788K | 4.00 |
| 15 April 2025 | 3.1M | +2.4% | 1.3M | 2.35 |
| 31 March 2025 | 3.0M | +17.8% | 1.2M | 2.55 |
| 14 March 2025 | 2.5M | +1.8% | 571K | 4.45 |
| 28 February 2025 | 2.5M | -22.5% | 878K | 2.84 |
| 14 February 2025 | 3.2M | +9.4% | 669K | 4.81 |
| 31 January 2025 | 2.9M | -6.6% | 676K | 4.35 |
| 15 January 2025 | 3.2M | -5.8% | 682K | 4.62 |
| 31 December 2024 | 3.3M | -4.1% | 615K | 5.44 |
| 13 December 2024 | 3.5M | +2.8% | 518K | 6.73 |
| 29 November 2024 | 3.4M | -9.2% | 865K | 3.92 |
| 15 November 2024 | 3.7M | +1.2% | 944K | 3.96 |
| 31 October 2024 | 3.7M | -23.6% | 939K | 3.94 |
| 15 October 2024 | 4.8M | +7.4% | 628K | 7.71 |
| 30 September 2024 | 4.5M | +1.2% | 628K | 7.17 |
| 13 September 2024 | 4.5M | +18.1% | 751K | 5.93 |
| 30 August 2024 | 3.8M | -16.5% | 1.1M | 3.56 |
| 15 August 2024 | 4.5M | +4.4% | 1.0M | 4.34 |
| 31 July 2024 | 4.3M | -3.7% | 740K | 5.84 |
| 15 July 2024 | 4.5M | +22.2% | 1.0M | 4.47 |
| 28 June 2024 | 3.7M | +72.7% | 2.9M | 1.26 |
| 14 June 2024 | 2.1M | -14.1% | 604K | 3.52 |
| 31 May 2024 | 2.5M | -2.4% | 618K | 4.01 |
| 15 May 2024 | 2.5M | -3.2% | 470K | 5.41 |
| 30 April 2024 | 2.6M | +5.0% | 473K | 5.55 |
| 15 April 2024 | 2.5M | -10.6% | 491K | 5.10 |
| 28 March 2024 | 2.8M | +4.2% | 582K | 4.81 |
| 15 March 2024 | 2.7M | -11.5% | 676K | 3.97 |
| 29 February 2024 | 3.0M | -23.9% | 1.5M | 2.00 |
| 15 February 2024 | 4.0M | -0.5% | 1.3M | 3.16 |
| 31 January 2024 | 4.0M | -7.4% | 593K | 6.76 |
| 12 January 2024 | 4.3M | -8.5% | 544K | 7.96 |
| 29 December 2023 | 4.7M | -5.3% | 431K | 10.96 |
| 15 December 2023 | 5.0M | -1.9% | 690K | 7.23 |
| 30 November 2023 | 5.1M | -2.1% | 532K | 9.56 |
| 15 November 2023 | 5.2M | -1.3% | 659K | 7.88 |
| 31 October 2023 | 5.3M | -1.7% | 659K | 7.99 |
| 13 October 2023 | 5.4M | +3.9% | 747K | 7.17 |
| 29 September 2023 | 5.2M | +0.0% | 603K | 8.55 |
| 15 September 2023 | 5.2M | -2.7% | 807K | 6.39 |
| 31 August 2023 | 5.3M | -1.5% | 376K | 14.08 |
| 15 August 2023 | 5.4M | +1.7% | 546K | 9.85 |
| 31 July 2023 | 5.3M | +6.8% | 588K | 9.01 |
| 14 July 2023 | 5.0M | -0.5% | 427K | 11.59 |
| 30 June 2023 | 5.0M | +0.5% | 729K | 6.84 |
| 15 June 2023 | 5.0M | -1.9% | 397K | 12.48 |
| 31 May 2023 | 5.1M | -1.3% | 611K | 8.27 |
| 15 May 2023 | 5.1M | +0.9% | 582K | 8.79 |
| 28 April 2023 | 5.1M | +2.2% | 841K | 6.04 |
| 14 April 2023 | 5.0M | -4.2% | 802K | 6.19 |
| 31 March 2023 | 5.2M | +5.1% | 836K | 6.20 |
| 15 March 2023 | 4.9M | -8.5% | 828K | 5.96 |
| 28 February 2023 | 5.4M | +5.6% | 1.1M | 5.03 |
| 15 February 2023 | 5.1M | -4.3% | 676K | 7.55 |
| 31 January 2023 | 5.3M | -6.2% | 754K | 7.07 |
| 13 January 2023 | 5.7M | +11.1% | 765K | 7.43 |
| 30 December 2022 | 5.1M | -5.3% | 629K | 8.13 |
| 15 December 2022 | 5.4M | +8.2% | 822K | 6.57 |
| 30 November 2022 | 5.0M | -10.2% | 754K | 6.62 |
| 15 November 2022 | 5.6M | -7.9% | 744K | 7.47 |
| 31 October 2022 | 6.0M | +25.6% | 950K | 6.35 |
| 14 October 2022 | 4.8M | +5.8% | 1.2M | 4.09 |
| 30 September 2022 | 4.5M | +3.6% | 903K | 5.03 |
| 15 September 2022 | 4.4M | +4.3% | 1.3M | 3.30 |
| 31 August 2022 | 4.2M | -15.9% | 783K | 5.37 |
| 15 August 2022 | 5.0M | +1.4% | 1.8M | 2.71 |
| 29 July 2022 | 4.9M | -1.2% | 543K | 9.08 |
| 15 July 2022 | 5.0M | +4.0% | 690K | 7.23 |
| 30 June 2022 | 4.8M | +1.1% | 1.1M | 4.50 |
| 15 June 2022 | 4.7M | -15.7% | 891K | 5.32 |
| 31 May 2022 | 5.6M | -4.0% | 766K | 7.34 |
| 13 May 2022 | 5.9M | -1.0% | 894K | 6.56 |
| 29 April 2022 | 5.9M | +2.2% | 966K | 6.13 |
| 14 April 2022 | 5.8M | +11.7% | 896K | 6.46 |
| 31 March 2022 | 5.2M | +9.5% | 697K | 7.44 |
| 15 March 2022 | 4.7M | +3.8% | 851K | 5.56 |
| 28 February 2022 | 4.6M | +3.7% | 816K | 5.59 |
| 15 February 2022 | 4.4M | +8.2% | 751K | 5.85 |
| 31 January 2022 | 4.1M | +2.9% | 839K | 4.84 |
| 14 January 2022 | 3.9M | +11.9% | 769K | 5.13 |
| 31 December 2021 | 3.5M | -6.0% | 1.2M | 2.95 |
| 15 December 2021 | 3.8M | -4.9% | 695K | 5.40 |
| 30 November 2021 | 4.0M | -2.4% | 690K | 5.73 |
| 15 November 2021 | 4.0M | +4.8% | 658K | 6.15 |
| 29 October 2021 | 3.9M | -0.5% | 730K | 5.30 |
| 15 October 2021 | 3.9M | -3.2% | 395K | 9.84 |
| 30 September 2021 | 4.0M | -9.2% | 694K | 5.78 |
| 15 September 2021 | 4.4M | -8.5% | 443K | 9.97 |
| 31 August 2021 | 4.8M | -3.5% | 550K | 8.78 |
| 13 August 2021 | 5.0M | -1.1% | 873K | 5.73 |
| 30 July 2021 | 5.1M | +20.0% | 559K | 9.06 |
| 15 July 2021 | 4.2M | -2.4% | 532K | 7.94 |
| 30 June 2021 | 4.3M | -6.6% | 937K | 4.62 |
| 15 June 2021 | 4.6M | +9.2% | 675K | 6.85 |
| 28 May 2021 | 4.2M | -6.3% | 388K | 10.92 |
| 14 May 2021 | 4.5M | +9.5% | 469K | 9.64 |
| 30 April 2021 | 4.1M | +0.6% | 463K | 8.93 |
| 15 April 2021 | 4.1M | +12.4% | 377K | 10.88 |
| 31 March 2021 | 3.7M | -1.8% | 462K | 7.90 |
| 15 March 2021 | 3.7M | +0.5% | 539K | 6.90 |
| 26 February 2021 | 3.7M | +4.9% | 507K | 7.29 |
| 12 February 2021 | 3.5M | -4.7% | 676K | 5.21 |
| 29 January 2021 | 3.7M | -4.3% | 721K | 5.13 |
| 15 January 2021 | 3.9M | +10.8% | 1.0M | 3.79 |
| 31 December 2020 | 3.5M | -4.8% | 468K | 7.45 |
| 15 December 2020 | 3.7M | -3.1% | 362K | 10.13 |
| 30 November 2020 | 3.8M | +1.5% | 477K | 7.92 |
| 13 November 2020 | 3.7M | +3.9% | 606K | 6.15 |
| 30 October 2020 | 3.6M | +6.0% | 414K | 8.66 |
| 15 October 2020 | 3.4M | +3.9% | 340K | 9.95 |
| 30 September 2020 | 3.3M | -9.1% | 523K | 6.23 |
| 15 September 2020 | 3.6M | -10.8% | 446K | 8.03 |
| 31 August 2020 | 4.0M | -5.7% | 341K | 11.79 |
| 14 August 2020 | 4.3M | -0.0% | 410K | 10.40 |
| 31 July 2020 | 4.3M | -9.8% | 478K | 8.92 |
| 15 July 2020 | 4.7M | -13.1% | 693K | 6.82 |
| 30 June 2020 | 5.4M | -7.0% | 1.2M | 4.61 |
| 15 June 2020 | 5.9M | +11.8% | 590K | 9.91 |
| 29 May 2020 | 5.2M | +0.6% | 611K | 8.57 |
| 15 May 2020 | 5.2M | +2.4% | 876K | 5.94 |
| 30 April 2020 | 5.1M | -5.0% | 804K | 6.32 |
| 15 April 2020 | 5.3M | +9.1% | 690K | 7.75 |
| 31 March 2020 | 4.9M | +1.0% | 969K | 5.06 |
| 13 March 2020 | 4.9M | -4.6% | 703K | 6.91 |
| 28 February 2020 | 5.1M | +0.2% | 674K | 7.56 |
| 14 February 2020 | 5.1M | +1.3% | 763K | 6.66 |
| 31 January 2020 | 5.0M | +4.5% | 608K | 8.25 |
| 15 January 2020 | 4.8M | +8.6% | 558K | 8.61 |
| 31 December 2019 | 4.4M | -10.5% | 608K | 7.27 |
| 13 December 2019 | 4.9M | -10.7% | 643K | 7.69 |
| 29 November 2019 | 5.5M | -12.0% | 1.3M | 4.39 |
| 15 November 2019 | 6.3M | -2.3% | 513K | 12.27 |
| 31 October 2019 | 6.4M | +0.5% | 683K | 9.42 |
| 15 October 2019 | 6.4M | +1.7% | 557K | 11.49 |
| 30 September 2019 | 6.3M | +2.1% | 721K | 8.74 |
| 13 September 2019 | 6.2M | +0.9% | 725K | 8.50 |
| 30 August 2019 | 6.1M | +3.7% | 688K | 8.87 |
| 15 August 2019 | 5.9M | +2.6% | 835K | 7.05 |
| 31 July 2019 | 5.7M | +7.5% | 723K | 7.94 |
| 15 July 2019 | 5.3M | +7.4% | 596K | 8.95 |
| 28 June 2019 | 5.0M | -3.3% | 673K | 7.39 |
| 14 June 2019 | 5.1M | -4.7% | 723K | 7.10 |
| 31 May 2019 | 5.4M | +7.2% | 870K | 6.20 |
| 15 May 2019 | 5.0M | -13.1% | 2.1M | 2.45 |
| 30 April 2019 | 5.8M | +4.9% | 718K | 8.06 |
| 15 April 2019 | 5.5M | +3.1% | 721K | 7.65 |
| 29 March 2019 | 5.4M | -7.4% | 649K | 8.24 |
| 15 March 2019 | 5.8M | +11.4% | 821K | 7.04 |
| 28 February 2019 | 5.2M | -4.4% | 684K | 7.58 |
| 15 February 2019 | 5.4M | -5.6% | 786K | 6.90 |
| 31 January 2019 | 5.7M | -9.9% | 895K | 6.42 |
| 15 January 2019 | 6.4M | +0.5% | 1.0M | 6.24 |
| 31 December 2018 | 6.3M | +1.6% | 1.0M | 6.31 |
| 14 December 2018 | 6.2M | +7.9% | 813K | 7.69 |
| 30 November 2018 | 5.8M | +1.6% | 702K | 8.25 |
| 15 November 2018 | 5.7M | -10.5% | 1.2M | 4.78 |
| 31 October 2018 | 6.4M | +9.5% | 809K | 7.87 |
| 15 October 2018 | 5.8M | -3.4% | 755K | 7.71 |
| 28 September 2018 | 6.0M | +1.3% | 797K | 7.56 |
| 14 September 2018 | 5.9M | -0.5% | 1.1M | 5.51 |
| 31 August 2018 | 6.0M | +10.1% | 1.0M | 5.80 |
| 15 August 2018 | 5.4M | +8.4% | 1.3M | 4.20 |
| 31 July 2018 | 5.0M | -1.6% | 677K | 7.40 |
| 13 July 2018 | 5.1M | -2.3% | 529K | 9.62 |
| 29 June 2018 | 5.2M | +1.5% | 618K | 8.44 |
| 15 June 2018 | 5.1M | +2.7% | 691K | 7.43 |
| 31 May 2018 | 5.0M | -13.0% | 665K | 7.51 |
| 15 May 2018 | 5.7M | -0.0% | 1.2M | 4.61 |
| 30 April 2018 | 5.7M | +0.2% | 805K | 7.13 |
| 13 April 2018 | 5.7M | +20.7% | 1.8M | 3.15 |
| 29 March 2018 | 4.7M | -1.3% | 1.1M | 4.31 |
| 15 March 2018 | 4.8M | -1.4% | 871K | 5.52 |
| 28 February 2018 | 4.9M | +2.2% | 512K | 9.54 |
| 15 February 2018 | 4.8M | -6.2% | 831K | 5.75 |
| 31 January 2018 | 5.1M | -13.4% | 1.1M | 4.64 |
| 12 January 2018 | 5.9M | +1.6% | 732K | 8.03 |
| 29 December 2017 | 5.8M | 685K | 8.44 |
Shares in millions (M) or thousands (K); hold the pointer on a figure for the exact count. FINRA publishes consolidated short interest twice a month, about ten days after each settlement.