Costco Wholesale Corporation
MX ˙ BMV ˙ US22160K1051
SecurityMX:COST / Costco Wholesale Corporation
InstitutionTamar Securities, LLC
Latest Disclosed Ownership778 shares
Latest Disclosed Value $ 775,663
Tamar Securities, LLC reports 5.47% decrease in ownership of COST / Costco Wholesale Corporation

On May 14, 2026 - Tamar Securities, LLC filed a 13F-HR form disclosing ownership of 778 shares of Costco Wholesale Corporation (MX:COST) valued at $775,663 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 823 shares of Costco Wholesale Corporation. This represents a change in shares of -5.47% 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)
2026-05-14 2026-03-31 13F COSTCO WHOLESALE COM 22160K105 778 -45 -5.47 776 9.31 0.0830
2026-02-13 2025-12-31 13F COSTCO WHSL CORP COM 22160K105 823 -58 -6.58 710 -13.01 0.0749
2025-11-14 2025-09-30 13F COSTCO WHSL CORP COM 22160K105 881 24 2.80 815 -3.89 0.0927
2025-08-11 2025-06-30 13F COSTCO WHSL CORP COM 22160K105 857 15 1.78 849 6.53 0.1029
2025-05-15 2025-03-31 13F COSTCO WHSL CORP COM 22160K105 842 5 0.60 796 3.78 0.1079
2025-01-22 2024-12-31 13F COSTCO WHSL CORP COM 22160K105 837 -85 -9.22 767 -6.00 0.1058
2024-10-16 2024-09-30 13F COSTCO WHSL CORP COM 22160K105 922 66 7.71 817 12.24 0.1148
2024-10-10 2024-06-30 13F COSTCO WHSL CORP COM 22160K105 856 0 0.00 728 15.95 0.1180
2024-05-13 2024-03-31 13F COSTCO WHSL CORP COM 22160K105 856 194 29.31 627 43.81 0.1058
2024-01-25 2023-12-31 13F COSTCO WHSL CORP COM 22160K105 662 -20 -2.93 437 13.25 0.0857
2023-11-14 2023-09-30 13F COSTCO WHSL CORP COM 22160K105 682 122 21.79 385 27.91 0.0929
2024-10-10 2023-06-30 13F COSTCO WHSL CORP COM 22160K105 560 -20 -3.45 302 4.51 0.0741
2024-10-10 2023-03-31 13F COSTCO WHSL CORP COM 22160K105 580 -1,123 -65.94 288 -62.93 0.0827
2023-02-10 2022-12-31 13F COSTCO WHSL CORP COM 22160K105 1,703 14 0.83 777 -2.63 0.2466
2022-11-07 2022-09-30 13F COSTCO WHSL CORP COM 22160K105 1,689 7 0.42 798 -0.99 0.2553
2022-08-05 2022-06-30 13F COSTCO WHSL CORP COM 22160K105 1,682 47 2.87 806 -14.35 0.2646
2022-04-27 2022-03-31 13F COSTCO WHSL CORP COM 22160K105 1,635 406 33.03 941 34.81 0.2626
2022-02-14 2021-12-31 13F COSTCO WHSL CORP COM 22160K105 1,229 -73 -5.61 698 19.32 0.2057
2021-10-19 2021-09-30 13F COSTCO WHSL CORP COM 22160K105 1,302 -63 -4.62 585 8.33 0.2113
2021-08-06 2021-06-30 13F COSTCO WHSL CORP COM 22160K105 1,365 -6 -0.44 540 11.80 0.2079
2021-05-11 2021-03-31 13F COSTCO WHSL CORP COM 22160K105 1,371 35 2.62 483 -3.98 0.1868
2021-01-27 2020-12-31 13F COSTCO WHSL CORP COM 22160K105 1,336 102 8.27 503 14.84 0.2859
2020-11-05 2020-09-30 13F COSTCO WHSL CORP COM 22160K105 1,234 52 4.40 438 22.35 0.2722
2020-09-10 2020-06-30 13F COSTCO WHSL CORP COM 22160K105 1,182 1,182 358 0.2853
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.