Costco Wholesale Corporation
MX ˙ BMV ˙ US22160K1051
SecurityMX:COST / Costco Wholesale Corporation
InstitutionCorundum Group, Inc.
Latest Disclosed Ownership1,479 shares
Latest Disclosed Value $ 1,473,720
Corundum Group, Inc. reports 7.33% decrease in ownership of COST / Costco Wholesale Corporation

On April 20, 2026 - Corundum Group, Inc. filed a 13F-HR form disclosing ownership of 1,479 shares of Costco Wholesale Corporation (MX:COST) valued at $1,473,720 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 12, 2026 disclosing 1,596 shares of Costco Wholesale Corporation. This represents a change in shares of -7.33% 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)
2026-04-20 2026-03-31 13F COSTCO WHOLESALE CORP- CS 22160K105 1,479 -117 -7.33 1,474 7.05 0.4926
2026-01-12 2025-12-31 13F COSTCO WHOLESALE CORP- CS 22160K105 1,596 251 18.66 1,376 10.61 0.4618
2025-10-24 2025-09-30 13F COSTCO WHOLESALE CORP- CS 22160K105 1,345 -26 -1.90 1,245 -8.33 0.5115
2025-07-21 2025-06-30 13F COSTCO WHOLESALE CORP- CS 22160K105 1,371 6 0.44 1,357 5.19 0.6001
2025-04-23 2025-03-31 13F COSTCO WHOLESALE CORP- CS 22160K105 1,365 -629 -31.54 1,291 -29.39 0.6192
2025-01-16 2024-12-31 13F COSTCO WHOLESALE CORP- CS 22160K105 1,994 627 45.87 1,827 50.87 0.6822
2024-10-21 2024-09-30 13F COSTCO WHOLESALE CORP- CS 22160K105 1,367 -689 -33.51 1,212 -30.68 0.5529
2024-07-17 2024-06-30 13F COSTCO WHOLESALE CORP- CS 22160K105 2,056 607 41.89 1,748 64.66 0.6828
2024-04-15 2024-03-31 13F COSTCO WHOLESALE CORP- CS 22160K105 1,449 -48 -3.21 1,062 7.39 0.5120
2024-01-24 2023-12-31 13F COSTCO WHOLESALE CORP- CS 22160K105 1,497 35 2.39 988 19.76 0.4954
2023-10-17 2023-09-30 13F COSTCO WHOLESALE CORP- CS 22160K105 1,462 276 23.27 826 29.31 0.4693
2023-07-21 2023-06-30 13F COSTCO WHOLESALE CORP- CS 22160K105 1,186 -1,013 -46.07 639 -41.58 0.3185
2023-04-24 2023-03-31 13F COSTCO WHOLESALE CORP- CS 22160K105 2,199 630 40.15 1,093 0.5168
2023-01-12 2022-12-31 13F COSTCO WHOLESALE CORP- CS 22160K105 1,569 933 146.70 1 -100.00 0.4043
2022-10-18 2022-09-30 13F COSTCO WHOLESALE CORP- CS 22160K105 636 10 1.60 300 0.00 0.1887
2022-07-25 2022-06-30 13F COSTCO WHOLESALE CORP- CS 22160K105 626 -1,084 -63.39 300 -69.54 0.2027
2022-05-02 2022-03-31 13F COSTCO WHOLESALE CORP- CS 22160K105 1,710 1,181 223.25 985 228.33 0.9155
2022-02-07 2021-12-31 13F COSTCO WHOLESALE CORP- CS 22160K105 529 529 300 0.1953
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.