William Blair Investment Management
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William Blair Investment Management’s Power Integrations POWI Stock Holding History

William Blair Investment Management’s Portfolio POWI Stock Details POWI Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		$122M Buy
+2,380,677
New +$109M 0.4% 68
2025
Q2 		– Sell
-7,005
Closed -$354K – 451
2025
Q1 		$354K Sell
7,005
-3,183
-31% -$190K ﹤0.01% 398
2024
Q4 		$629K Sell
10,188
-80
-0.8% -$5.09K ﹤0.01% 380
2024
Q3 		$658K Buy
10,268
+2,078
+25% +$137K ﹤0.01% 361
2024
Q2 		$575K Sell
8,190
-287,791
-97% -$20.7M ﹤0.01% 364
2024
Q1 		$21.2M Buy
295,981
+9,796
+3% +$731K 0.05% 301
2023
Q4 		$23.5M Buy
286,185
+35,708
+14% +$2.74M 0.07% 272
2023
Q3 		$19.1M Buy
250,477
+50,003
+25% +$4.28M 0.06% 283
2023
Q2 		$19M Sell
200,474
-13,103
-6% -$1.09M 0.06% 288
2023
Q1 		$18.1M Buy
213,577
+60,402
+39% +$5.02M 0.06% 288
2022
Q4 		$11M Buy
153,175
+3,399
+2% +$243K 0.04% 305
2022
Q3 		$9.63M Sell
149,776
-265,971
-64% -$19.9M 0.04% 307
2022
Q2 		$31.2M Sell
415,747
-45,174
-10% -$3.67M 0.12% 202
2022
Q1 		$42.7M Buy
460,921
+79,718
+21% +$6.95M 0.13% 176
2021
Q4 		$35.4M Buy
381,203
+210,984
+124% +$20.7M 0.1% 233
2021
Q3 		$16.9M Buy
+170,219
New +$16.5M 0.05% 328
2018
Q3 		– Sell
-7,020
Closed -$256K – 477
2018
Q2 		$256K Buy
+7,020
New +$254K ﹤0.01% 468

Other funds holding POWI

BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
VPM
Vanguard Portfolio Management Malvern, Pennsylvania $1.91T AUM
Neuberger Berman Group
Neuberger Berman Group New York $131B AUM 28.36% 1-Year Est. Return
Wellington Management Group
Wellington Management Group Boston, Massachusetts $535B AUM 26.23% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return
VCM
Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM
SCM
Snyder Capital Management San Francisco, California $5.16B AUM 26.72% 1-Year Est. Return
DGI
Disciplined Growth Investors Minneapolis, Minnesota $4.89B AUM 33.85% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.61T AUM 30.72% 1-Year Est. Return
Morgan Stanley
Morgan Stanley New York $1.66T AUM 25.57% 1-Year Est. Return

William Blair Investment Management's POWI Position: Q1 2026 in Review

William Blair Investment Management opened a new position in Power Integrations (POWI) in Q1 2026: 2,380,677 shares worth $122M. The stake represents 0.4% of the portfolio and ranks #68 among its holdings. This is a return to the name: William Blair Investment Management previously reported a position in POWI as recently as Q1 2025.

William Blair Investment Management first reported a position in POWI in Q2 2018 and has held it in 17 quarters since. 308 funds tracked by Wall St. Rank hold POWI as of Q1 2026.

  • William Blair Investment Management held 2,380,677 shares of Power Integrations worth $122M as of Q1 2026.
  • Power Integrations was a new William Blair Investment Management position in Q1 2026.
  • Power Integrations made up 0.4% of William Blair Investment Management's portfolio in Q1 2026, its #68 holding.
  • William Blair Investment Management first reported a position in Power Integrations in Q2 2018 and has held it in 17 quarters since.
  • 308 funds tracked by Wall St. Rank held Power Integrations as of Q1 2026.

Based on William Blair Investment Management's 13F filing for Q1 2026, filed 8 May 2026.