Costco Wholesale Corporation
US ˙ NasdaqGS ˙ US22160K1051

SecurityCOST / Costco Wholesale Corporation
InstitutionMairs & Power Inc
Latest Disclosed Ownership2,963 shares
Latest Disclosed Value $ 2,952,422
Mairs & Power Inc reports 1.02% increase in ownership of COST / Costco Wholesale Corporation

On May 13, 2026 - Mairs & Power Inc filed a 13F-HR form disclosing ownership of 2,963 shares of Costco Wholesale Corporation (US:COST) valued at $2,952,422 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 2,933 shares of Costco Wholesale Corporation. This represents a change in shares of 1.02% during the quarter. The current value of the position is $2,849,902 USD.

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)
2026-05-13 2026-03-31 13F COSTCO WHOLESALE COM 22160K105 2,963 30 1.02 2,952 16.73 0.0302
2026-02-17 2025-12-31 13F COSTCO WHSL CORP COM 22160K105 2,933 -288 -8.94 2,529 -15.16 0.0243
2025-11-14 2025-09-30 13F COSTCO WHSL CORP COM 22160K105 3,221 33 1.04 2,981 -5.52 0.0280
2025-08-14 2025-06-30 13F COSTCO WHSL CORP COM 22160K105 3,188 488 18.07 3,156 23.58 0.0312
2025-05-15 2025-03-31 13F COSTCO WHSL CORP COM 22160K105 2,700 -39 -1.42 2,554 1.75 0.0266
2025-02-14 2024-12-31 13F COSTCO WHSL CORP COM 22160K105 2,739 -358 -11.56 2,510 -8.60 0.0243
2024-11-14 2024-09-30 13F COSTCO WHSL CORP COM 22160K105 3,097 -637 -17.06 2,746 -13.49 0.0258
2024-08-14 2024-06-30 13F COSTCO WHSL CORP COM 22160K105 3,734 -845 -18.45 3,174 -5.40 0.0307
2024-05-15 2024-03-31 13F COSTCO WHSL CORP COM 22160K105 4,579 -357 -7.23 3,355 2.95 0.0325
2024-02-14 2023-12-31 13F COSTCO WHSL CORP COM 22160K105 4,936 1,486 43.07 3,258 67.16 0.0343
2023-11-14 2023-09-30 13F COSTCO WHSL CORP COM 22160K105 3,450 -175 -4.83 1,949 -0.10 0.0229
2023-08-14 2023-06-30 13F COSTCO WHSL CORP COM 22160K105 3,625 21 0.58 1,952 8.99 0.0212
2023-05-15 2023-03-31 13F COSTCO WHSL CORP COM 22160K105 3,604 473 15.11 1,791 25.26 0.0207
2023-02-14 2022-12-31 13F COSTCO WHSL CORP COM 22160K105 3,131 0 0.00 1,429 -3.38 0.0172
2022-11-14 2022-09-30 13F COSTCO WHSL CORP COM 22160K105 3,131 -45 -1.42 1,479 -2.83 0.0187
2022-08-15 2022-06-30 13F COSTCO WHSL CORP COM 22160K105 3,176 -2 -0.06 1,522 -16.83 0.0182
2022-05-16 2022-03-31 13F COSTCO WHSL CORP COM 22160K105 3,178 4 0.13 1,830 1.55 0.0184
2022-02-14 2021-12-31 13F COSTCO WHSL CORP COM 22160K105 3,174 518 19.50 1,802 51.05 0.0167
2021-11-15 2021-09-30 13F COSTCO WHSL CORP COM 22160K105 2,656 -581 -17.95 1,193 -6.87 0.0119
2021-08-16 2021-06-30 13F COSTCO WHSL CORP COM 22160K105 3,237 -81 -2.44 1,281 9.49 0.0127
2021-05-14 2021-03-31 13F COSTCO WHSL CORP COM 22160K105 3,318 -114 -3.32 1,170 -9.51 0.0123
2021-02-16 2020-12-31 13F COSTCO WHSL CORP COM 22160K105 3,432 80 2.39 1,293 8.66 0.0144
2020-11-16 2020-09-30 13F COSTCO WHSL CORP COM 22160K105 3,352 -141 -4.04 1,190 12.37 0.0149
2020-08-14 2020-06-30 13F COSTCO WHSL CORP COM 22160K105 3,493 0 0.00 1,059 6.33 0.0138
2020-05-15 2020-03-31 13F COSTCO WHSL CORP COM 22160K105 3,493 0 0.00 996 -3.02 0.0145
2020-02-14 2019-12-31 13F Costco Wholesale COM 22160K105 3,493 40 1.16 1,027 3.22 0.0117
2019-11-14 2019-09-30 13F Costco Wholesale COM 22160K105 3,453 31 0.91 995 10.07 0.0120
2019-08-14 2019-06-30 13F Costco Wholesale COM 22160K105 3,422 -31 -0.90 904 8.13 0.0108
2019-05-15 2019-03-31 13F Costco Wholesale COM 22160K105 3,453 -69 -1.96 836 16.60 0.0102
2019-02-14 2018-12-31 13F Costco Wholesale COM 22160K105 3,522 0 0.00 717 -13.30 0.0097
2018-11-14 2018-09-30 13F Costco Wholesale COM 22160K105 3,522 -150 -4.08 827 7.82 0.0096
2018-08-14 2018-06-30 13F Costco Wholesale COM 22160K105 3,672 200 5.76 767 17.28 0.0095
2018-05-15 2018-03-31 13F Costco Wholesale COM 22160K105 3,472 596 20.72 654 22.24 0.0081
2018-02-14 2017-12-31 13F Costco Wholesale COM 22160K105 2,876 -126 -4.20 535 8.52 0.0062
2017-11-14 2017-09-30 13F Costco Wholesale COM 22160K105 3,002 -54 -1.77 493 0.82 0.0059
2017-08-14 2017-06-30 13F Costco Wholesale COM 22160K105 3,056 -46 -1.48 489 -5.96 0.0059
2017-05-15 2017-03-31 13F Costco Wholesale COM 22160K105 3,102 -163 -4.99 520 -0.57 0.0064
2017-02-14 2016-12-31 13F Costco Wholesale COM 22160K105 3,265 26 0.80 523 5.87 0.0067
2016-11-14 2016-09-30 13F Costco Wholesale COM 22160K105 3,239 341 11.77 494 8.57 0.0065
2016-08-15 2016-06-30 13F Costco Wholesale COM 22160K105 2,898 0 0.00 455 -0.44 0.0061
2016-05-16 2016-03-31 13F Costco Wholesale COM 22160K105 2,898 0 0.00 457 -2.35 0.0065
2016-02-16 2015-12-31 13F Costco Wholesale COM 22160K105 2,898 -240 -7.65 468 3.08 0.0070
2015-11-16 2015-09-30 13F Costco Wholesale COM 22160K105 3,138 340 12.15 454 20.11 0.0071
2015-08-14 2015-06-30 13F Costco Wholesale COM 22160K105 2,798 157 5.94 378 -5.50 0.0054
2015-05-15 2015-03-31 13F Costco Wholesale COM 22160K105 2,641 0 0.00 400 6.95 0.0055
2015-02-17 2014-12-31 13F Costco Wholesale COM 22160K105 2,641 450 20.54 374 36.00 0.0052
2014-11-14 2014-09-30 13F Costco Wholesale COM 22160K105 2,191 -75 -3.31 275 5.36 0.0040
2014-08-14 2014-06-30 13F Costco Wholesale COM 22160K105 2,266 -248 -9.86 261 -7.12 0.0037
2014-05-15 2014-03-31 13F Costco Wholesale COM 22160K105 2,514 545 27.68 281 20.09 0.0042
2014-02-14 2013-12-31 13F Costco Wholesale COM 22160K105 1,969 -200 -9.22 234 -6.40 0.0036
2013-11-14 2013-09-30 13F Costco Wholesale COM 22160K105 2,169 203 10.33 250 15.21 0.0043
2013-08-14 2013-06-30 13F Costco Wholesale COM 22160K105 1,966 1,966 217 0.0041
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.