William Blair Investment Management’s Costco COST Stock Holding History
Bought
Maintained
Sold
| Quarter | Market Value | Status | Shares |
Change in Stake | Trade Value | Portfolio Weight | Portfolio Position | |
|---|---|---|---|---|---|---|---|---|
|
2026
Q2 | $186M | Sell |
199,355
-103,113
| -34% | -$103M | 0.56% | 44 |
|
|
2026
Q1 | $301M | Sell |
302,468
-26,000
| -8% | -$25.3M | 1% | 13 |
|
|
2025
Q4 | $283M | Buy |
328,468
+5,728
| +2% | +$5.19M | 0.79% | 21 |
|
|
2025
Q3 | $299M | Sell |
322,740
-53,745
| -14% | -$51.5M | 0.77% | 22 |
|
|
2025
Q2 | $373M | Buy |
376,485
+22,906
| +6% | +$22.8M | 0.99% | 14 |
|
|
2025
Q1 | $334M | Buy |
353,579
+16,394
| +5% | +$16M | 0.94% | 17 |
|
|
2024
Q4 | $309M | Sell |
337,185
-4,680
| -1% | -$4.34M | 0.75% | 21 |
|
|
2024
Q3 | $303M | Sell |
341,865
-24,201
| -7% | -$21M | 0.75% | 24 |
|
|
2024
Q2 | $311M | Buy |
366,066
+9,662
| +3% | +$7.54M | 0.82% | 23 |
|
|
2024
Q1 | $261M | Sell |
356,404
-37,764
| -10% | -$27M | 0.67% | 35 |
|
|
2023
Q4 | $260M | Sell |
394,168
-43,333
| -10% | -$25.7M | 0.76% | 29 |
|
|
2023
Q3 | $247M | Buy |
437,501
+62,752
| +17% | +$34.6M | 0.82% | 26 |
|
|
2023
Q2 | $202M | Buy |
374,749
+13,246
| +4% | +$6.7M | 0.65% | 42 |
|
|
2023
Q1 | $180M | Sell |
361,503
-123,661
| -25% | -$60.7M | 0.63% | 44 |
|
|
2022
Q4 | $221M | Buy |
485,164
+22,970
| +5% | +$11.2M | 0.85% | 29 |
|
|
2022
Q3 | $218M | Buy |
462,194
+29,250
| +7% | +$15.2M | 0.86% | 29 |
|
|
2022
Q2 | $208M | Buy |
432,944
+94,454
| +28% | +$47.9M | 0.77% | 30 |
|
|
2022
Q1 | $195M | Buy |
338,490
+29,582
| +10% | +$15.5M | 0.58% | 58 |
|
|
2021
Q4 | $175M | Buy |
308,908
+94,552
| +44% | +$48.4M | 0.47% | 76 |
|
|
2021
Q3 | $96.3M | Sell |
214,356
-4,132
| -2% | -$1.82M | 0.27% | 108 |
|
|
2021
Q2 | $86.4M | Buy |
218,488
+2,938
| +1% | +$1.11M | 0.27% | 116 |
|
|
2021
Q1 | $76M | Buy |
215,550
+35,925
| +20% | +$12.5M | 0.25% | 117 |
|
|
2020
Q4 | $67.7M | Sell |
179,625
-49,385
| -22% | -$18.5M | 0.23% | 116 |
|
|
2020
Q3 | $81.3M | Buy |
229,010
+93,807
| +69% | +$31.5M | 0.32% | 101 |
|
|
2020
Q2 | $41M | Buy |
135,203
+10,588
| +8% | +$3.22M | 0.17% | 137 |
|
|
2020
Q1 | $35.5M | Sell |
124,615
-1,536
| -1% | -$466K | 0.17% | 131 |
|
|
2019
Q4 | $37.1M | Sell |
126,151
-9,031
| -7% | -$2.68M | 0.15% | 140 |
|
|
2019
Q3 | $38.9M | Sell |
135,182
-15,010
| -10% | -$4.22M | 0.17% | 131 |
|
|
2019
Q2 | $39.7M | Buy |
150,192
+22,517
| +18% | +$5.61M | 0.17% | 132 |
|
|
2019
Q1 | $30.9M | Buy |
127,675
+62,504
| +96% | +$13.7M | 0.13% | 145 |
|
|
2018
Q4 | $13.3M | Buy |
65,171
+2,016
| +3% | +$450K | 0.07% | 258 |
|
|
2018
Q3 | $14.8M | Sell |
63,155
-17,124
| -21% | -$3.86M | 0.05% | 304 |
|
|
2018
Q2 | $16.8M | Sell |
80,279
-3,712
| -4% | -$733K | 0.06% | 273 |
|
|
2018
Q1 | $15.8M | Sell |
83,991
-11,118
| -12% | -$2.1M | 0.06% | 274 |
|
|
2017
Q4 | $17.7M | Sell |
95,109
-326,485
| -77% | -$56.4M | 0.07% | 259 |
|
|
2017
Q3 | $69.3M | Buy |
421,594
+58,441
| +16% | +$9.18M | 0.25% | 124 |
|
|
2017
Q2 | $58.1M | Sell |
363,153
-109,039
| -23% | -$18.8M | 0.21% | 125 |
|
|
2017
Q1 | $79.2M | Sell |
472,192
-97,682
| -17% | -$16.4M | 0.3% | 107 |
|
|
2016
Q4 | $91.2M | Sell |
569,874
-42,055
| -7% | -$6.42M | 0.36% | 88 |
|
|
2016
Q3 | $93.3M | Buy |
611,929
+16,226
| +3% | +$2.62M | 0.35% | 89 |
|
|
2016
Q2 | $93.5M | Sell |
595,703
-169,088
| -22% | -$25.6M | 0.37% | 91 |
|
|
2016
Q1 | $121M | Buy |
764,791
+113,047
| +17% | +$17.1M | 0.48% | 79 |
|
|
2015
Q4 | $105M | Buy |
651,744
+31,927
| +5% | +$5.05M | 0.43% | 85 |
|
|
2015
Q3 | $89.6M | Buy |
+619,817
| New | +$88.4M | 0.18% | 159 |
|
Other funds holding COST
William Blair Investment Management's COST Position: Q2 2026 in Review
William Blair Investment Management reduced its Costco (COST) stake by 34% in Q2 2026, selling an estimated $103M and leaving 199,355 shares worth $186M. The position accounts for 0.56% of the portfolio, ranked #44.
William Blair Investment Management first reported a position in COST in Q3 2015 and has held it in 44 quarters since. The position peaked at $373M in Q2 2025. 4,224 funds tracked by Wall St. Rank hold COST as of Q2 2026.
- William Blair Investment Management held 199,355 shares of Costco worth $186M as of Q2 2026.
- William Blair Investment Management sold 103,113 Costco shares in Q2 2026, an estimated $103M.
- Costco made up 0.56% of William Blair Investment Management's portfolio in Q2 2026, its #44 holding.
- William Blair Investment Management first reported a position in Costco in Q3 2015 and has held it in 44 quarters since.
- William Blair Investment Management's Costco position peaked at $373M in Q2 2025.
- 4,224 funds tracked by Wall St. Rank held Costco as of Q2 2026.
Based on William Blair Investment Management's 13F filing for Q2 2026, filed 12 Aug 2026.