iRhythm Holdings, Inc.
US ˙ NasdaqGS ˙ US4500561067

SecurityIRTC / iRhythm Holdings, Inc.
InstitutionQUANTITATIVE MASTER SERIES LLC - Master Small Cap Index Series
Latest Disclosed Ownership54,846 shares
Latest Disclosed Value $ 8,444,090
QUANTITATIVE MASTER SERIES LLC - Master Small Cap Index Series reports 2.94% increase in ownership of IRTC / iRhythm Holdings, Inc.

On August 26, 2025 - QUANTITATIVE MASTER SERIES LLC - Master Small Cap Index Series filed a NPORT-P form disclosing ownership of 54,846 shares of iRhythm Holdings, Inc. (US:IRTC) valued at $8,444,090 USD as of June 30, 2025. The entity filed a previous NPORT-P on May 28, 2025 disclosing 53,278 shares of iRhythm Holdings, Inc.. This represents a change in shares of 2.94% during the quarter. The current value of the position is $5,929,127 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)
2025-08-26 2025-06-30 NP iRhythm Technologies EC US4500561067 54,846 1,568 2.94 8,444 51.41 0.1896
2025-05-28 2025-03-31 NP iRhythm Technologies EC US4500561067 53,278 565 1.07 5,577 17.34 0.1338
2025-02-25 2024-12-31 NP iRhythm Technologies EC US4500561067 52,713 -9,208 -14.87 4,753 3.39 0.1038
2024-11-26 2024-09-30 NP iRhythm Technologies EC US4500561067 61,921 3,601 6.17 4,597 -26.76 0.0869
2024-08-26 2024-06-30 NP iRhythm Technologies EC US4500561067 58,320 4,564 8.49 6,278 0.67 0.1278
2024-05-28 2024-03-31 NP iRhythm Technologies EC US4500561067 53,756 -2,130 -3.81 6,236 4.23 0.1301
2024-02-26 2023-12-31 NP iRhythm Technologies EC US4500561067 55,886 3,840 7.38 5,982 21.96 0.1277
2023-11-28 2023-09-30 NP iRhythm Technologies EC US4500561067 52,046 -969 -1.83 4,906 -11.30 0.1280
2023-08-25 2023-06-30 NP iRhythm Technologies EC US4500561067 53,015 5,132 10.72 5,531 -6.87 0.1312
2023-05-26 2023-03-31 NP iRhythm Technologies EC US4500561067 47,883 796 1.69 5,939 34.65 0.1581
2023-02-24 2022-12-31 NP iRhythm Technologies EC US4500561067 47,087 -971 -2.02 4,411 -26.74 0.1213
2022-11-25 2022-09-30 NP iRhythm Technologies EC US4500561067 48,058 1,952 4.23 6,021 20.88 0.1725
2022-08-25 2022-06-30 NP iRhythm Technologies EC US4500561067 46,106 208 0.45 4,981 -31.09 0.1375
2022-05-26 2022-03-31 NP iRhythm Technologies EC US4500561067 45,898 772 1.71 7,228 36.10 0.1684
2022-02-25 2021-12-31 NP iRhythm Technologies EC US4500561067 45,126 0 0.00 5,311 100.98 0.1152
2021-11-24 2021-09-30 NP iRhythm Technologies EC US4500561067 45,126 0 0.00 2,643 -11.76 0.0582
2021-08-26 2021-06-30 NP iRhythm Technologies EC US4500561067 45,126 1,259 2.87 2,994 -50.85 0.0642
2021-05-27 2021-03-31 NP iRhythm Technologies EC US4500561067 43,867 -1,231 -2.73 6,091 -43.06 0.1381
2021-02-25 2020-12-31 NP iRhythm Technologies EC US4500561067 45,098 297 0.66 10,698 0.28 0.2741
2020-11-25 2020-09-30 NP iRhythm Technologies EC US4500561067 44,801 -980 -2.14 10,668 101.07 0.3423
2020-08-27 2020-06-30 NP iRhythm Technologies EC US4500561067 45,781 2,642 6.12 5,306 51.18 0.1734
2020-06-01 2020-03-31 NP iRhythm Technologies EC US4500561067 43,139 -716 -1.63 3,509 17.52 0.1435
2020-02-27 2019-12-31 NP iRhythm Technologies EC 450056106 43,855 6,101 16.16 2,986 6.76 0.0898
2019-11-27 2019-09-30 NP iRhythm Technologies EC US4500561067 37,754 37,754 2,798 0.0925
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.