Rhythm Pharmaceuticals, Inc.
MX ˙ BMV ˙ US76243J1051
SecurityMX:RYTM / Rhythm Pharmaceuticals, Inc.
InstitutionHarbor Capital Advisors, Inc.
Latest Disclosed Ownership30,353 shares
Latest Disclosed Value $ 2,640
Harbor Capital Advisors, Inc. reports 25.78% decrease in ownership of RYTM / Rhythm Pharmaceuticals, Inc.

On April 28, 2026 - Harbor Capital Advisors, Inc. filed a 13F-HR form disclosing ownership of 30,353 shares of Rhythm Pharmaceuticals, Inc. (MX:RYTM) valued at $2,640 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 20, 2026 disclosing 40,896 shares of Rhythm Pharmaceuticals, Inc.. This represents a change in shares of -25.78% during the quarter.

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.

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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)
2026-04-28 2026-03-31 13F Rhythm Pharmaceuticals COM 76243J105 30,353 -10,543 -25.78 3 -50.00 0.2138
2026-01-20 2025-12-31 13F Rhythm Pharmaceuticals COM 76243J105 40,896 3,691 9.92 4 33.33 0.3400
2025-10-15 2025-09-30 13F Rhythm Pharmaceuticals COM 76243J105 37,205 -49,341 -57.01 4 -40.00 0.2919
2025-07-09 2025-06-30 13F Rhythm Pharmaceuticals COM 76243J105 86,546 9,249 11.97 5 25.00 0.2297
2025-04-14 2025-03-31 13F Rhythm Pharmaceuticals COM 76243J105 77,297 47,045 155.51 4 300.00 0.1866
2025-01-10 2024-12-31 13F Rhythm Pharmaceuticals COM 76243J105 30,252 -11,116 -26.87 2 -50.00 0.0739
2024-10-29 2024-09-30 13F Rhythm Pharmaceuticals COM 76243J105 41,368 6,741 19.47 2 100.00 0.0942
2024-07-09 2024-06-30 13F Rhythm Pharmaceuticals COM 76243J105 34,627 11,846 52.00 1 0.1083
2024-05-13 2024-03-31 13F Rhythm Pharmaceuticals COM 76243J105 22,781 22,781 1 0.1290
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.