Rhythm Pharmaceuticals, Inc.
US ˙ NasdaqGM ˙ US76243J1051

SecurityRYTM / Rhythm Pharmaceuticals, Inc.
InstitutionFmr Llc
Latest Disclosed Ownership1,689,671 shares
Latest Disclosed Value $ 146,950,721
Fmr Llc reports 0.98% decrease in ownership of RYTM / Rhythm Pharmaceuticals, Inc.

On May 15, 2026 - Fmr Llc filed a 13F-HR form disclosing ownership of 1,689,671 shares of Rhythm Pharmaceuticals, Inc. (US:RYTM) valued at $146,950,687 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 1,706,317 shares of Rhythm Pharmaceuticals, Inc.. This represents a change in shares of -0.98% during the quarter. The current value of the position is $148,032,076 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

Upgrade to unlock premium data and export to Excel .

Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-15 2026-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,689,671 -16,646 -0.98 146,951 -19.54 0.0015
2026-02-17 2025-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,706,317 -438,866 -20.46 182,644 -15.69 0.0093
2025-11-13 2025-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 2,145,183 191,742 9.82 216,642 75.51 0.0113
2025-08-14 2025-06-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,953,441 265,066 15.70 123,438 38.02 0.0070
2025-05-12 2025-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,688,375 1,575,266 1,392.70 89,433 1,312.62 0.0057
2025-02-13 2024-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 113,109 62,814 124.89 6,332 140.36 0.0004
2024-11-13 2024-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 50,295 22,306 79.70 2,635 129.24 0.0002
2024-08-13 2024-06-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 27,989 -1,031 -3.55 1,149 -8.59 0.0001
2024-05-13 2024-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 29,020 -500,110 -94.52 1,257 -94.83 0.0001
2024-02-13 2023-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 529,130 -339,344 -39.07 24,324 22.18 0.0019
2023-11-13 2023-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 868,474 166,940 23.80 19,910 72.10 0.0017
2023-08-11 2023-06-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 701,534 2,710 0.39 11,568 -7.21 0.0010
2023-08-11 2023-03-31 13F/A-1 RHYTHM PHARMACEUTICALS COM 76243J105 698,824 -74,204 -9.60 12,467 -44.62 0.0011
2023-05-11 2023-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 698,824 -74,204 12,467 0.0002
2023-02-13 2022-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 773,028 -597,920 -43.61 22,511 -32.98 0.0022
2022-11-10 2022-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,370,948 813,954 146.13 33,588 1,352.77 0.0035
2022-08-12 2022-06-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 556,994 3,127 0.56 2,312 -63.77 0.0002
2022-05-13 2022-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 553,867 7,547 1.38 6,381 17.04 0.0005
2022-02-14 2021-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 546,320 463,042 556.02 5,452 401.10 0.0004
2022-02-14 2021-09-30 13F/A-1 RHYTHM PHARMACEUTICALS COM 76243J105 83,278 0 0.00 1,088 -33.29 0.0001
2021-11-15 2021-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 83,278 0 1,088 0.0000
2021-08-13 2021-06-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 83,278 0 0.00 1,631 -7.91 0.0001
2021-05-14 2021-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 83,278 36,100 76.52 1,771 26.23 0.0002
2021-02-08 2020-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 47,178 -13,420 -22.15 1,403 6.85 0.0001
2020-11-13 2020-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 60,598 -165,480 -73.20 1,313 -73.96 0.0001
2020-08-24 2020-06-30 13F/A-1 RHYTHM PHARMACEUTICALS COM 76243J105 226,078 0 0.00 5,042 46.53 0.0006
2020-08-13 2020-06-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 226,078 0 5,042 123.8672
2020-05-14 2020-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 226,078 -799,712 -77.96 3,441 -85.39 0.0005
2020-02-07 2019-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,025,790 -34,529 -3.26 23,552 2.88 0.0026
2019-11-13 2019-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,060,319 -137,700 -11.49 22,892 -13.14 0.0027
2019-08-13 2019-06-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,198,019 -391,488 -24.63 26,356 -39.51 0.0031
2019-05-13 2019-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,589,507 -100,500 -5.95 43,568 -4.09 0.0052
2019-02-13 2018-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,690,007 65,213 4.01 45,427 -4.15 0.0062
2018-11-09 2018-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,624,794 -200,840 -11.00 47,395 -16.95 0.0053
2018-08-10 2018-06-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,825,634 529,834 40.89 57,069 121.32 0.0067
2018-05-14 2018-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,295,800 -6,800 -0.52 25,786 -31.88 0.0031
2018-02-12 2017-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 1,302,600 1,302,600 37,854 0.0044
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.