Costco Wholesale Corporation
MX ˙ BMV ˙ US22160K1051
SecurityMX:COST / Costco Wholesale Corporation
InstitutionGrandfield & Dodd, Llc
Latest Disclosed Ownership4,778 shares
Latest Disclosed Value $ 4,760,943
Grandfield & Dodd, Llc reports 0.87% decrease in ownership of COST / Costco Wholesale Corporation

On May 7, 2026 - Grandfield & Dodd, Llc filed a 13F-HR form disclosing ownership of 4,778 shares of Costco Wholesale Corporation (MX:COST) valued at $4,760,943 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 10, 2026 disclosing 4,820 shares of Costco Wholesale Corporation. This represents a change in shares of -0.87% 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)
2026-05-07 2026-03-31 13F COSTCO WHOLESALE COM 22160K105 4,778 -42 -0.87 4,761 14.53 0.2688
2026-02-10 2025-12-31 13F COSTCO WHSL CORP COM 22160K105 4,820 -17 -0.35 4,156 -7.17 0.2354
2025-10-30 2025-09-30 13F COSTCO WHSL CORP COM 22160K105 4,837 -46 -0.94 4,477 -7.39 0.2540
2025-08-08 2025-06-30 13F COSTCO WHSL CORP COM 22160K105 4,883 221 4.74 4,834 9.64 0.2831
2025-05-02 2025-03-31 13F COSTCO WHSL CORP COM 22160K105 4,662 -35 -0.75 4,409 2.46 0.2734
2025-02-06 2024-12-31 13F COSTCO WHSL CORP COM 22160K105 4,697 -45 -0.95 4,304 2.35 0.2654
2024-11-08 2024-09-30 13F COSTCO WHSL CORP COM 22160K105 4,742 -455 -8.76 4,204 -4.82 0.2491
2024-08-09 2024-06-30 13F COSTCO WHSL CORP COM 22160K105 5,197 -15 -0.29 4,418 15.69 0.2797
2024-05-06 2024-03-31 13F COSTCO WHSL CORP COM 22160K105 5,212 -25 -0.48 3,819 10.47 0.2410
2024-01-31 2023-12-31 13F COSTCO WHSL CORP COM 22160K105 5,237 52 1.00 3,457 17.99 0.2389
2023-10-26 2023-09-30 13F COSTCO WHSL CORP COM 22160K105 5,185 -5 -0.10 2,929 4.83 0.2152
2023-08-08 2023-06-30 13F COSTCO WHSL CORP COM 22160K105 5,190 272 5.53 2,794 14.37 0.1953
2023-04-28 2023-03-31 13F COSTCO WHSL CORP COM 22160K105 4,918 -20 -0.41 2,444 8.39 0.1708
2023-01-20 2022-12-31 13F COSTCO WHSL CORP COM 22160K105 4,938 -174 -3.40 2,254 -6.47 0.1649
2022-11-04 2022-09-30 13F COSTCO WHSL CORP COM 22160K105 5,112 0 0.00 2,410 -1.63 0.1968
2022-08-01 2022-06-30 13F COSTCO WHSL CORP COM 22160K105 5,112 0 0.00 2,450 -16.67 0.1930
2022-04-19 2022-03-31 13F COSTCO WHSL CORP COM 22160K105 5,112 -65 -1.26 2,940 0.00 0.1995
2022-02-08 2021-12-31 13F COSTCO WHSL CORP COM 22160K105 5,177 -74 -1.41 2,940 24.58 0.1891
2021-10-28 2021-09-30 13F COSTCO WHSL CORP COM 22160K105 5,251 190 3.75 2,360 18.00 0.1647
2021-07-28 2021-06-30 13F COSTCO WHSL CORP COM 22160K105 5,061 56 1.12 2,000 13.64 0.1384
2021-04-22 2021-03-31 13F COSTCO WHSL CORP COM 22160K105 5,005 0 0.00 1,760 -6.88 0.1316
2021-01-29 2020-12-31 13F COSTCO WHSL CORP COM 22160K105 5,005 -35 -0.69 1,890 5.59 0.1483
2020-11-03 2020-09-30 13F COSTCO WHSL CORP COM 22160K105 5,040 22 0.44 1,790 17.76 0.1612
2020-07-24 2020-06-30 13F COSTCO WHSL CORP COM 22160K105 5,018 11 0.22 1,520 6.44 0.1471
2020-05-14 2020-03-31 13F COSTCO WHSL CORP COM 22160K105 5,007 208 4.33 1,428 1.20 0.1684
2020-02-07 2019-12-31 13F COSTCO WHSL CORP COM 22160K105 4,799 0 0.00 1,411 2.02 0.1285
2019-10-30 2019-09-30 13F COSTCO WHSL CORP COM 22160K105 4,799 0 0.00 1,383 9.07 0.1361
2019-07-29 2019-06-30 13F COSTCO WHSL CORP COM 22160K105 4,799 73 1.54 1,268 10.84 0.1253
2019-04-26 2019-03-31 13F COSTCO WHSL CORP COM 22160K105 4,726 0 0.00 1,144 18.80 0.1191
2019-02-12 2018-12-31 13F COSTCO WHSL CORP COM 22160K105 4,726 0 0.00 963 -13.24 0.1140
2018-11-02 2018-09-30 13F COSTCO WHSL CORP COM 22160K105 4,726 45 0.96 1,110 13.50 0.1144
2018-07-27 2018-06-30 13F COSTCO WHSL CORP COM 22160K105 4,681 -30 -0.64 978 10.14 0.1075
2018-05-04 2018-03-31 13F/A-1 COSTCO WHSL CORP COM 22160K105 4,711 -30 -0.63 888 0.68 0.0991
2018-05-04 2018-03-31 13F COSTCO WHSL CORP COM 22160K105 4,711 -30 888
2018-02-05 2017-12-31 13F COSTCO WHSL CORP COM 22160K105 4,741 -68 -1.41 882 11.65 0.0942
2017-11-03 2017-09-30 13F COSTCO WHSL CORP COM 22160K105 4,809 35 0.73 790 3.40 0.0887
2017-07-27 2017-06-30 13F COSTCO WHSL CORP COM 22160K105 4,774 -350 -6.83 764 -11.06 0.0903
2017-04-28 2017-03-31 13F COSTCO WHSL CORP COM 22160K105 5,124 -2,825 -35.54 859 -32.52 0.1061
2017-02-02 2016-12-31 13F COSTCO WHSL CORP COM 22160K105 7,949 0 0.00 1,273 5.03 0.1650
2016-10-24 2016-09-30 13F COSTCO WHSL CORP COM 22160K105 7,949 578 7.84 1,212 4.66 0.1592
2016-07-28 2016-06-30 13F COSTCO WHSL CORP COM 22160K105 7,371 -420 -5.39 1,158 -5.70 0.1621
2016-05-06 2016-03-31 13F COSTCO WHSL CORP COM 22160K105 7,791 -100 -1.27 1,228 -3.61 0.1777
2016-02-03 2015-12-31 13F COSTCO WHSL CORP COM 22160K105 7,891 -220 -2.71 1,274 8.61 0.1937
2015-11-02 2015-09-30 13F COSTCO WHSL CORP COM 22160K105 8,111 0 0.00 1,173 7.12 0.1967
2015-08-03 2015-06-30 13F COSTCO WHSL CORP COM 22160K105 8,111 -1,944 -19.33 1,095 -28.10 0.1675
2015-05-15 2015-03-31 13F COSTCO WHSL CORP COM 22160K105 10,055 0 0.00 1,523 6.88 0.2328
2015-02-05 2014-12-31 13F COSTCO WHSL CORP COM 22160K105 10,055 -30 -0.30 1,425 12.74 0.2203
2014-11-10 2014-09-30 13F COSTCO WHSL CORP COM 22160K105 10,085 30 0.30 1,264 9.15 0.1986
2014-08-14 2014-06-30 13F COSTCO WHSL CORP COM 22160K105 10,055 -4,000 -28.46 1,158 -26.24 0.1747
2014-05-06 2014-03-31 13F COSTCO WHSL CORP COM 22160K105 14,055 -40 -0.28 1,570 -6.44 0.2465
2014-02-06 2013-12-31 13F COSTCO WHSL CORP COM 22160K105 14,095 0 0.00 1,678 3.39 0.2726
2013-11-04 2013-09-30 13F COSTCO WHSL CORP COM 22160K105 14,095 150 1.08 1,623 5.25 0.2894
2013-08-01 2013-06-30 13F COSTCO WHSL CORP COM 22160K105 13,945 13,945 1,542 0.2921
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.