Costco Wholesale Corporation
MX ˙ BMV ˙ US22160K1051
SecurityMX:COST / Costco Wholesale Corporation
InstitutionRosenberg Matthew Hamilton
Latest Disclosed Ownership715 shares
Latest Disclosed Value $ 712,447
Rosenberg Matthew Hamilton reports 2.88% increase in ownership of COST / Costco Wholesale Corporation

On April 6, 2026 - Rosenberg Matthew Hamilton filed a 13F-HR form disclosing ownership of 715 shares of Costco Wholesale Corporation (MX:COST) valued at $712,447 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 5, 2026 disclosing 695 shares of Costco Wholesale Corporation. This represents a change in shares of 2.88% 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)
2026-04-06 2026-03-31 13F COSTCO WHOLESALE CORPORATION COM Stock 22160K105 715 20 2.88 712 18.86 0.1460
2026-01-05 2025-12-31 13F COSTCO WHSL CORP NEW COM Stock 22160K105 695 1 0.14 599 -6.70 0.1241
2025-11-10 2025-09-30 13F COSTCO WHSL CORP NEW COM Stock 22160K105 694 8 1.17 642 -5.45 0.1389
2025-07-28 2025-06-30 13F COSTCO WHSL CORP NEW COM Stock 22160K105 686 -13 -1.86 679 2.72 0.1579
2025-04-28 2025-03-31 13F COSTCO WHSL CORP NEW COM Stock 22160K105 699 25 3.71 661 7.13 0.1658
2025-01-14 2024-12-31 13F COSTCO WHSL CORP NEW COM Stock 22160K105 674 -49 -6.78 618 -3.59 0.1605
2024-10-28 2024-09-30 13F COSTCO WHSL CORP NEW COM Stock 22160K105 723 21 2.99 641 7.93 0.1677
2024-07-26 2024-06-30 13F COSTCO WHSL CORP NEW COM Stock 22160K105 702 -10 -1.40 594 15.59 0.1753
2024-04-22 2024-03-31 13F COSTCO WHSL CORP NEW COM Stock 22160K105 712 -6 -0.84 514 8.46 0.1484
2024-01-16 2023-12-31 13F COSTCO WHSL CORP NEW COM Stock 22160K105 718 7 0.98 474 17.96 0.1458
2023-10-11 2023-09-30 13F COSTCO WHSL CORP NEW COM Stock 22160K105 711 0 0.00 402 4.97 0.1338
2023-07-26 2023-06-30 13F COSTCO WHSL CORP NEW COM Stock 22160K105 711 -105 -12.87 383 -5.68 0.1294
2023-04-17 2023-03-31 13F COSTCO WHSL CORP NEW COM Stock 22160K105 816 0 0.00 405 8.87 0.1308
2023-01-19 2022-12-31 13F COSTCO WHSL CORP NEW COM Stock 22160K105 816 -20 -2.39 373 -5.82 0.1262
2022-10-21 2022-09-30 13F COSTCO WHSL CORP NEW COM Stock 22160K105 836 43 5.42 395 2.60 0.1527
2022-07-15 2022-06-30 13F COSTCO WHSL CORP NEW COM Stock 22160K105 793 8 1.02 385 -14.82 0.1452
2022-04-14 2022-03-31 13F COSTCO WHSL CORP NEW COM Stock 22160K105 785 49 6.66 452 8.13 0.1581
2022-01-20 2021-12-31 13F COSTCO WHSL NEW COM 22160K105 736 53 7.76 418 36.16 0.1488
2021-10-12 2021-09-30 13F COSTCO WHSL NEW COM 22160K105 683 177 34.98 307 53.50 0.1213
2021-07-26 2021-06-30 13F COSTCO WHSL CORP COM 22160K105 506 -13 -2.50 200 9.29 0.1041
2021-04-30 2021-03-31 13F COSTCO WHSL NEW COM 22160K105 519 -62 -10.67 183 -16.44 0.1044
2021-02-03 2020-12-31 13F COSTCO WHSL CORP COM 22160K105 581 62 11.95 219 19.02 0.1367
2020-10-16 2020-09-30 13F COSTCO WHSL CORP COM 22160K105 519 0 0.00 184 17.20 0.1352
2020-08-04 2020-06-30 13F COSTCO WHSL CORP COM 22160K105 519 -59 -10.21 157 -4.85 0.1250
2020-05-14 2020-03-31 13F COSTCO WHSL CORP COM 22160K105 578 578 165 0.1641
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.