Advanced Drainage Systems, Inc.
MX ˙ BMV ˙ US00790R1041
SecurityMX:WMS / Advanced Drainage Systems, Inc.
InstitutionRathbone Brothers plc
Latest Disclosed Ownership130,792 shares
Latest Disclosed Value $ 17,935,506
Rathbone Brothers plc reports 14.04% decrease in ownership of WMS / Advanced Drainage Systems, Inc.

On May 12, 2026 - Rathbone Brothers plc filed a 13F-HR form disclosing ownership of 130,792 shares of Advanced Drainage Systems, Inc. (MX:WMS) valued at $17,935,506 USD as of March 31, 2026. The entity filed a previous 13F-HR/A on February 6, 2026 disclosing 152,152 shares of Advanced Drainage Systems, Inc.. This represents a change in shares of -14.04% 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)
2026-05-12 2026-03-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 130,792 -21,360 -14.04 17,936 -18.61 0.0766
2026-02-06 2025-12-31 13F/A-1 ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 152,152 -5,073 -3.23 22,036 1.05 0.0872
2026-01-21 2025-12-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 152,152 -5,073 22,036 0.0872
2025-11-13 2025-09-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 157,225 -139,782 -47.06 21,807 -36.08 0.0885
2025-08-07 2025-06-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 297,007 2,694 0.92 34,114 6.68 0.1471
2025-05-13 2025-03-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 294,313 38,658 15.12 31,977 8.20 0.1545
2025-02-13 2024-12-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 255,655 26,078 11.36 29,554 -18.09 0.1431
2024-11-13 2024-09-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 229,577 22,607 10.92 36,080 8.69 0.1821
2024-08-09 2024-06-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 206,970 8,468 4.27 33,196 -2.91 0.1808
2024-05-14 2024-03-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 198,502 -2,179 -1.09 34,190 21.14 0.1973
2024-02-13 2023-12-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 200,681 4,688 2.39 28,224 26.51 0.1819
2023-11-13 2023-09-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 195,993 -25,616 -11.56 22,310 -11.52 0.1618
2023-08-04 2023-06-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 221,609 34,731 18.58 25,215 60.23 0.2353
2023-05-12 2023-03-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 186,878 31,768 20.48 15,737 23.77 0.1609
2023-02-14 2022-12-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 155,110 25,919 20.06 12,714 -20.87 0.1432
2022-11-14 2022-09-30 13F/A-1 ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 129,191 2,622 2.07 16,067 40.94 0.1982
2022-11-03 2022-09-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 129,191 2,622 16,067 0.1982
2022-08-12 2022-06-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 126,569 26,342 26.28 11,400 -4.27 0.1307
2022-05-11 2022-03-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 100,227 36,896 58.26 11,908 38.13 0.1215
2022-02-10 2021-12-31 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 63,331 28,029 79.40 8,621 125.74 0.0838
2021-11-04 2021-09-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 35,302 10,237 40.84 3,819 30.70 0.0411
2021-07-30 2021-06-30 13F ADVANCED DRAINAGE SYSTEM INC USD0.01 COM 00790R104 25,065 25,065 2,922 0.0325
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.