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William Blair Investment Management

William Blair Investment Management Portfolio holdings

AUM $30.3B
1-Year Est. Return 33.75%
This Fund
S&P 500
This Quarter Est. Return
-0.1%
1 Year Est. Return
+33.75%
3 Year Est. Return
+108.55%
5 Year Est. Return
+126.9%
10 Year Est. Return
+771.69%
AUM
$30.3B
AUM Growth
-$5.59B
Cap. Flow
-$4.09B
Cap. Flow %
-13.52%
Top 10 Hldgs %
30.62%
Holding
459
New
46
Increased
157
Reduced
205
Closed
46

Top Buys

Rank Stock Value
1
AZN icon
AstraZeneca
AZN
+$370M
2
AKAM icon
Akamai
AKAM
+$162M
3
BWA icon
BorgWarner
BWA
+$152M
4
APH icon
Amphenol
APH
+$152M
5
SYNA icon
Synaptics
SYNA
+$129M

Top Sells

Rank Stock Value
1
NVDA icon
NVIDIA
NVDA
+$309M
2
SE icon
Sea Limited
SE
+$302M
3
AMZN icon
Amazon
AMZN
+$269M
4
MSFT icon
Microsoft
MSFT
+$248M
5
CIEN icon
Ciena
CIEN
+$214M

Sector Composition

Rank Sector Weight
1 Technology 36.13%
2 Healthcare 12.59%
3 Industrials 11.81%
4 Financials 11.55%
5 Consumer Discretionary 10.11%
Name Market Value Portfolio Weight Shares or Principal Change
in Stake 		Capital Flow
AGX icon
251
Argan
AGX
$7.61B
$21M 0.07%
38,555
-24,806
-39% -$10.1M
PANW icon
252
Palo Alto Networks
PANW
$259B
$20.9M 0.07%
130,453
-6,395
-5% -$1.07M
MMS icon
253
Maximus
MMS
$3.2B
$20.8M 0.07%
324,170
+10,576
+3% +$859K
BRC icon
254
Brady Corp
BRC
$4.54B
$20.6M 0.07%
254,182
-98,352
-28% -$8.55M
ULS icon
255
UL Solutions
ULS
$18.2B
$20.1M 0.07%
234,392
-141,647
-38% -$11.2M
INTR icon
256
Inter&Co
INTR
$2.45B
$20M 0.07%
2,515,463
-3,079,733
-55% -$26.7M
NTST
257
NETSTREIT Corp
NTST
$2.13B
$20M 0.07%
1,061,598
+33,126
+3% +$638K
AMPX icon
258
Amprius Technologies
AMPX
$1.38B
$19.7M 0.07%
1,170,131
+185,225
+19% +$2.41M
AEHR icon
259
Aehr Test Systems
AEHR
$2.52B
$19M 0.06%
513,293
+17,621
+4% +$564K
REXR icon
260
Rexford Industrial Realty
REXR
$8.63B
$19M 0.06%
580,797
-354,314
-38% -$13.3M
ABM icon
261
ABM Industries
ABM
$2.84B
$18.8M 0.06%
487,701
+16,581
+4% +$717K
LITE icon
262
Lumentum
LITE
$55.4B
$18.7M 0.06%
26,579
-113,124
-81% -$62.1M
VRTX icon
263
Vertex Pharmaceuticals
VRTX
$122B
$17.7M 0.06%
39,547
-188
-0.5% -$87.7K
BGSI
264
Boyd Group Services
BGSI
$3B
$17.3M 0.06%
135,248
-6,700
-5% -$1.08M
IAG icon
265
IAMGOLD
IAG
$8.5B
$17M 0.06%
905,946
-315,665
-26% -$6.26M
PENG
266
Penguin Solutions Inc
PENG
$2.69B
$17M 0.06%
966,164
+31,076
+3% +$591K
LRCX icon
267
Lam Research
LRCX
$365B
$17M 0.06%
79,447
-31,221
-28% -$6.98M
UMH
268
UMH Properties
UMH
$1.32B
$16.9M 0.06%
1,169,982
+36,916
+3% +$571K
SHO icon
269
Sunstone Hotel Investors
SHO
$2.2B
$16.7M 0.06%
1,855,709
+57,835
+3% +$531K
DY icon
270
Dycom Industries
DY
$12.7B
$16.7M 0.06%
49,293
-29,646
-38% -$11.1M
ADC icon
271
Agree Realty
ADC
$9.66B
$16.5M 0.05%
218,993
-133,717
-38% -$10.1M
AR icon
272
Antero Resources
AR
$10.5B
$16.3M 0.05%
384,775
-241,645
-39% -$8.82M
RUSHA icon
273
Rush Enterprises Class A
RUSHA
$5.98B
$15.8M 0.05%
238,823
+7,481
+3% +$493K
WING icon
274
Wingstop
WING
$3.74B
$15.3M 0.05%
+98,480
New +$23.7M
VERX icon
275
Vertex
VERX
$2.05B
$15.2M 0.05%
1,279,170
+63,998
+5% +$997K
9 10
11
12 13

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William Blair Investment Management's Q1 2026 Portfolio in Review

As of Q1 2026, William Blair Investment Management held 459 positions worth $30.3B, down 16% from $35.9B the previous quarter. Its ten largest holdings account for 31% of the portfolio.

William Blair Investment Management withdrew a net $4.09B in Q1 2026, closing 46 positions and reducing 205 holdings. Its most notable exit was Sea Limited, an estimated $302M position sold in full.

By sector, the portfolio is most concentrated in Technology at 36% of assets, down from 38% a quarter earlier, followed by Healthcare and Industrials.

Against the trend, William Blair Investment Management opened a new position in Akamai worth $186M.

  • William Blair Investment Management's largest Q1 2026 buy was Akamai: 1,619,060 shares worth $186M.
  • William Blair Investment Management added most to AstraZeneca in Q1 2026, an estimated $370M increase.
  • William Blair Investment Management's biggest Q1 2026 reduction was NVIDIA, cutting an estimated $309M.
  • William Blair Investment Management fully exited Sea Limited in Q1 2026, selling an estimated $302M.
  • William Blair Investment Management's ten largest holdings make up 31% of its $30.3B portfolio in Q1 2026.
  • William Blair Investment Management opened 46 new positions and closed 46 in Q1 2026.
  • William Blair Investment Management's portfolio value fell 16% quarter-over-quarter to $30.3B.

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