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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
+788.31%
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
THR
176
DELISTED
Thermon Group Holdings
THR
$32.6M 0.11%
647,539
-239,912
-27% -$11.2M
KRG icon
177
Kite Realty
KRG
$5.36B
$32.5M 0.11%
1,325,260
+40,656
+3% +$1M
VSH icon
178
Vishay Intertechnology
VSH
$5.43B
$32.5M 0.11%
1,803,297
+208,848
+13% +$3.8M
VVV icon
179
Valvoline
VVV
$4.51B
$32.3M 0.11%
958,268
+258,541
+37% +$8.94M
VCYT icon
180
Veracyte
VCYT
$3.8B
$31.9M 0.11%
989,687
+199,262
+25% +$7.38M
IDA icon
181
Idacorp
IDA
$8.2B
$31.8M 0.11%
222,487
-353,590
-61% -$48.5M
SR icon
182
Spire
SR
$4.85B
$31.7M 0.1%
350,033
+11,017
+3% +$967K
NWN icon
183
Northwest Natural Holdings
NWN
$2.12B
$31.6M 0.1%
594,204
+19,006
+3% +$942K
WLY icon
184
John Wiley & Sons Class A
WLY
$2.66B
$31.3M 0.1%
821,987
+27,087
+3% +$878K
MIRM icon
185
Mirum Pharmaceuticals
MIRM
$6.14B
$31M 0.1%
335,669
-1,032
-0.3% -$97.1K
FRME icon
186
First Merchants
FRME
$2.67B
$30.6M 0.1%
789,882
+25,978
+3% +$1.01M
ACVA icon
187
ACV Auctions
ACVA
$1.3B
$30.6M 0.1%
7,212,623
-3,679,063
-34% -$24.1M
LNTH icon
188
Lantheus
LNTH
$6.59B
$30.3M 0.1%
399,551
-122,626
-23% -$8.8M
DIOD icon
189
Diodes
DIOD
$4.84B
$30.1M 0.1%
441,562
-30,563
-6% -$1.93M
JCAP
190
Jefferson Capital
JCAP
$1.31B
$30M 0.1%
1,559,949
+75,840
+5% +$1.6M
FCPT icon
191
Four Corners Property Trust
FCPT
$2.75B
$29.4M 0.1%
1,243,103
+187,267
+18% +$4.64M
ABCB icon
192
Ameris Bancorp
ABCB
$5.89B
$29.2M 0.1%
374,709
+12,515
+3% +$993K
PODD icon
193
Insulet
PODD
$9.79B
$29.2M 0.1%
139,130
-6,681
-5% -$1.68M
ESAB icon
194
ESAB
ESAB
$5.71B
$29.2M 0.1%
301,883
+96,865
+47% +$11.2M
TCBI icon
195
Texas Capital Bancshares
TCBI
$4.32B
$29.1M 0.1%
306,821
-161,179
-34% -$15.7M
LXP icon
196
LXP Industrial Trust
LXP
$3.57B
$28.9M 0.1%
623,925
+19,761
+3% +$966K
USPH icon
197
US Physical Therapy
USPH
$1.22B
$28.3M 0.09%
377,863
+7,156
+2% +$586K
ICUI icon
198
ICU Medical
ICUI
$4.61B
$28.1M 0.09%
217,903
+7,137
+3% +$1.03M
NWE icon
199
NorthWestern Energy
NWE
$4.43B
$28.1M 0.09%
426,480
+13,152
+3% +$890K
SIGI icon
200
Selective Insurance
SIGI
$5.73B
$27.9M 0.09%
370,419
+12,952
+4% +$1.06M
6 7
8
9 10

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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.