William Blair Investment Management
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William Blair Investment Management’s West Pharmaceutical WST Stock Holding History

William Blair Investment Management’s Portfolio WST Stock Details WST Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q2 		$150M Buy
417,309
+377,584
+950% +$115M 0.45% 66
2026
Q1 		$9.96M Sell
39,725
-1,517
-4% -$377K 0.03% 314
2025
Q4 		$11.3M Buy
41,242
+437
+1% +$120K 0.03% 309
2025
Q3 		$10.7M Sell
40,805
-325,347
-89% -$79.1M 0.03% 318
2025
Q2 		$80.1M Buy
366,152
+13,314
+4% +$2.85M 0.21% 114
2025
Q1 		$79M Sell
352,838
-287,897
-45% -$79.3M 0.22% 115
2024
Q4 		$210M Buy
640,735
+563,705
+732% +$177M 0.51% 53
2024
Q3 		$23.1M Buy
77,030
+10,545
+16% +$3.23M 0.06% 287
2024
Q2 		$21.9M Buy
66,485
+5,492
+9% +$1.94M 0.06% 288
2024
Q1 		$24.1M Buy
+60,993
New +$22.6M 0.06% 286
2023
Q2 		– Sell
-1,595
Closed -$553K – 424
2023
Q1 		$553K Buy
+1,595
New +$466K ﹤0.01% 356
2019
Q1 		– Sell
-749,634
Closed -$73.5M – 427
2018
Q4 		$73.5M Sell
749,634
-684,983
-48% -$74.3M 0.37% 91
2018
Q3 		$177M Sell
1,434,617
-194,122
-12% -$21.8M 0.61% 51
2018
Q2 		$162M Buy
1,628,739
+318,397
+24% +$29.3M 0.6% 50
2018
Q1 		$116M Buy
1,310,342
+37,935
+3% +$3.55M 0.44% 76
2017
Q4 		$126M Buy
1,272,407
+383,646
+43% +$37.6M 0.49% 68
2017
Q3 		$85.6M Buy
+888,761
New +$80.4M 0.31% 108
2015
Q4 		– Sell
-7,345
Closed -$398K – 473
2015
Q3 		$398K Buy
+7,345
New +$428K ﹤0.01% 1013

Other funds holding WST

BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
Vanguard Capital Management
Vanguard Capital Management Malvern, Pennsylvania $4.68T AUM
Vanguard Portfolio Management
Vanguard Portfolio Management Malvern, Pennsylvania $2.22T AUM
Fidelity Investments
Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $3.37T AUM 44.26% 1-Year Est. Return
Artisan Partners
Artisan Partners Milwaukee, Wisconsin $63.1B AUM 35.51% 1-Year Est. Return
Bank of New York Mellon
Bank of New York Mellon New York $609B AUM 40.19% 1-Year Est. Return
GIM
Generation Investment Management London, United Kingdom $10.3B AUM 4.84% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.88T AUM 44.46% 1-Year Est. Return
T. Rowe Price Investment Management
T. Rowe Price Investment Management Baltimore, Maryland $153B AUM 38.14% 1-Year Est. Return

William Blair Investment Management's WST Position: Q2 2026 in Review

William Blair Investment Management increased its West Pharmaceutical (WST) stake by 950% in Q2 2026, buying an estimated $115M and bringing the position to 417,309 shares worth $150M. The position accounts for 0.45% of the portfolio, ranked #66.

William Blair Investment Management first reported a position in WST in Q3 2015 and has held it in 18 quarters since. The position peaked at $210M in Q4 2024. 830 funds tracked by Wall St. Rank hold WST as of Q2 2026.

  • William Blair Investment Management held 417,309 shares of West Pharmaceutical worth $150M as of Q2 2026.
  • William Blair Investment Management bought 377,584 West Pharmaceutical shares in Q2 2026, an estimated $115M.
  • West Pharmaceutical made up 0.45% of William Blair Investment Management's portfolio in Q2 2026, its #66 holding.
  • William Blair Investment Management first reported a position in West Pharmaceutical in Q3 2015 and has held it in 18 quarters since.
  • William Blair Investment Management's West Pharmaceutical position peaked at $210M in Q4 2024.
  • 830 funds tracked by Wall St. Rank held West Pharmaceutical as of Q2 2026.

Based on William Blair Investment Management's 13F filing for Q2 2026, filed 12 Aug 2026.