Rhythm Pharmaceuticals, Inc.
US ˙ NasdaqGM ˙ US76243J1051

SecurityRYTM / Rhythm Pharmaceuticals, Inc.
InstitutionLazard Asset Management Llc
Latest Disclosed Ownership32,888 shares
Latest Disclosed Value $ 2,860,269
Lazard Asset Management Llc reports 28.61% increase in ownership of RYTM / Rhythm Pharmaceuticals, Inc.

On May 15, 2026 - Lazard Asset Management Llc filed a 13F-HR form disclosing ownership of 32,888 shares of Rhythm Pharmaceuticals, Inc. (US:RYTM) valued at $2,860,269 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 25,571 shares of Rhythm Pharmaceuticals, Inc.. This represents a change in shares of 28.61% during the quarter. The current value of the position is $2,841,523 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.

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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)
2026-05-15 2026-03-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 32,888 7,317 28.61 2,860 4.49 0.0025
2026-02-17 2025-12-31 13F RHYTHM PHARMACEUTICALS COM 76243J105 25,571 -4,668 -15.44 2,737 -10.35 0.0046
2025-11-14 2025-09-30 13F RHYTHM PHARMACEUTICALS COM 76243J105 30,239 -69,206 -69.59 3,054 50,783.33 0.0041
2025-08-14 2025-06-30 13F RHYTHM PHARMAC Common Stock 76243J105 99,445 -3,757 -3.64 6 20.00 0.0086
2025-05-15 2025-03-31 13F RHYTHM PHARMAC Common Stock 76243J105 103,202 -3,059 -2.88 5 0.00 0.0084
2025-02-14 2024-12-31 13F RHYTHM PHARMAC Common Stock 76243J105 106,261 106,261 6 0.0087
2024-08-14 2024-06-30 13F RHYTHM PHARMAC Common Stock 76243J105 0 -1,733 -100.00 0 0.0000
2024-07-09 2024-03-31 13F/A-1 RHYTHM PHARMAC Common Stock 76243J105 1,733 -124 -6.68 0 0.0001
2024-05-14 2024-03-31 13F RHYTHM PHARMAC Common Stock 76243J105 1,733 -124 0 0.0001
2024-02-14 2023-12-31 13F RHYTHM PHARMAC Common Stock 76243J105 1,857 1,857 0 0.0001
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.