Costco Wholesale Corporation
MX ˙ BMV ˙ US22160K1051
SecurityMX:COST / Costco Wholesale Corporation
InstitutionRathbone Brothers plc
Latest Disclosed Ownership235,962 shares
Latest Disclosed Value $ 235,097,199
Rathbone Brothers plc reports 14.09% decrease in ownership of COST / Costco Wholesale Corporation

On May 12, 2026 - Rathbone Brothers plc filed a 13F-HR form disclosing ownership of 235,962 shares of Costco Wholesale Corporation (MX:COST) valued at $235,097,199 USD as of March 31, 2026. The entity filed a previous 13F-HR/A on February 6, 2026 disclosing 274,655 shares of Costco Wholesale Corporation. This represents a change in shares of -14.09% 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.

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)
2026-05-12 2026-03-31 13F COSTCO CORP NPV COM 22160K105 235,962 -38,693 -14.09 235,097 -0.73 1.0045
2026-02-06 2025-12-31 13F/A-1 COSTCO CORP NPV COM 22160K105 274,655 5,866 2.18 236,814 -4.81 0.9375
2026-01-21 2025-12-31 13F COSTCO CORP NPV COM 22160K105 274,655 5,866 236,814 0.9375
2025-11-13 2025-09-30 13F COSTCO CORP NPV COM 22160K105 268,789 -7,341 -2.66 248,782 -8.96 1.0102
2025-08-07 2025-06-30 13F COSTCO CORP NPV COM 22160K105 276,130 -4,217 -1.50 273,258 3.06 1.1785
2025-05-13 2025-03-31 13F COSTCO CORP NPV COM 22160K105 280,347 -12,111 -4.14 265,141 -1.08 1.2813
2025-02-13 2024-12-31 13F COSTCO CORP NPV COM 22160K105 292,458 -7,824 -2.61 268,024 0.71 1.2975
2024-11-13 2024-09-30 13F COSTCO CORP NPV COM 22160K105 300,282 -5,708 -1.87 266,144 2.33 1.3430
2024-08-09 2024-06-30 13F COSTCO CORP NPV COM 22160K105 305,990 2,463 0.81 260,096 17.00 1.4166
2024-05-14 2024-03-31 13F COSTCO CORP NPV COM 22160K105 303,527 165 0.05 222,308 10.99 1.2829
2024-02-13 2023-12-31 13F COSTCO CORP NPV COM 22160K105 303,362 -21,275 -6.55 200,296 9.21 1.2908
2023-11-13 2023-09-30 13F COSTCO CORP NPV COM 22160K105 324,637 21,038 6.93 183,396 12.20 1.3300
2023-08-04 2023-06-30 13F COSTCO CORP NPV COM 22160K105 303,599 -2,242 -0.73 163,458 7.54 1.5255
2023-05-12 2023-03-31 13F COSTCO CORP NPV COM 22160K105 305,841 1,807 0.59 151,994 9.50 1.5540
2023-02-14 2022-12-31 13F COSTCO CORP NPV COM 22160K105 304,034 3,612 1.20 138,813 -2.17 1.5630
2022-11-14 2022-09-30 13F/A-1 COSTCO CORP NPV COM 22160K105 300,422 -2,929 -0.97 141,898 -2.43 1.7507
2022-11-03 2022-09-30 13F COSTCO CORP NPV COM 22160K105 300,422 -2,929 141,898 1.7507
2022-08-12 2022-06-30 13F COSTCO CORP NPV COM 22160K105 303,351 337 0.11 145,434 -16.64 1.6672
2022-05-11 2022-03-31 13F COSTCO CORP NPV COM 22160K105 303,014 -8,585 -2.76 174,459 -1.38 1.7800
2022-02-10 2021-12-31 13F COSTCO CORP NPV COM 22160K105 311,599 -5,476 -1.73 176,904 24.14 1.7192
2021-11-04 2021-09-30 13F COSTCO CORP NPV COM 22160K105 317,075 -2,613 -0.82 142,506 12.64 1.5332
2021-07-30 2021-06-30 13F COSTCO CORP NPV COM 22160K105 319,688 51,707 19.30 126,510 33.91 1.4054
2021-05-14 2021-03-31 13F COSTCO CORP NPV COM 22160K105 267,981 25,875 10.69 94,475 3.60 1.2098
2021-02-11 2020-12-31 13F COSTCO CORP NPV COM 22160K105 242,106 18,496 8.27 91,193 14.92 1.2948
2020-11-13 2020-09-30 13F COSTCO CORP NPV COM 22160K105 223,610 48,610 27.78 79,352 49.60 1.3578
2020-08-07 2020-06-30 13F COSTCO CORP NPV COM 22160K105 175,000 28,799 19.70 53,043 27.17 1.0768
2020-05-04 2020-03-31 13F COSTCO CORP NPV COM 22160K105 146,201 19,767 15.63 41,710 12.25 1.2148
2020-02-11 2019-12-31 13F COSTCO CORP NPV COM 22160K105 126,434 -471 -0.37 37,157 1.62 0.9781
2019-11-13 2019-09-30 13F COSTCO CORP NPV COM 22160K105 126,905 550 0.44 36,565 9.54 1.0385
2019-08-12 2019-06-30 13F COSTCO CORP NPV COM 22160K105 126,355 441 0.35 33,382 9.45 1.0451
2019-05-09 2019-03-31 13F COSTCO CORP NPV COM 22160K105 125,914 -479 -0.38 30,500 18.44 1.0029
2019-02-12 2018-12-31 13F COSTCO CORP NPV COM 22160K105 126,393 124,590 6,910.15 25,751 5,973.35 0.9869
2018-10-12 2018-09-30 13F COSTCO CORP NPV COM 22160K105 1,803 1,803 424 0.0144
2018-01-24 2017-12-31 13F COSTCO CORP NPV COM 22160K105 0 -129,240 -100.00 0 -100.00
2017-10-24 2017-09-30 13F COSTCO CORP NPV COM 22160K105 129,240 0 0.00 21,232 2.72 0.9244
2017-08-10 2017-06-30 13F COSTCO CORP NPV COM 22160K105 129,240 15,200 13.33 20,669 8.07 0.9209
2017-04-06 2017-03-31 13F COSTCO CORP NPV COM 22160K105 114,040 -1,000 -0.87 19,126 3.84 0.8719
2017-02-02 2016-12-31 13F COSTCO CORP NPV COM 22160K105 115,040 0 0.00 18,419 4.98 0.9231
2016-10-24 2016-09-30 13F COSTCO CORP NPV COM 22160K105 115,040 0 0.00 17,545 -2.91 0.9062
2016-08-03 2016-06-30 13F COSTCO CORP NPV COM 22160K105 115,040 -29 -0.03 18,070 -0.39 0.9957
2016-04-08 2016-03-31 13F COSTCO CORP NPV COM 22160K105 115,069 40 0.03 18,140 2.97 1.1030
2016-01-19 2015-12-31 13F COSTCO CORP NPV COM 22160K105 115,029 5,029 4.57 17,617 10.78 1.1186
2015-10-27 2015-09-30 13F COSTCO CORP NPV COM 22160K105 110,000 110,000 15,902 1.0598
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.