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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
CMC icon
301
Commercial Metals
CMC
$7.53B
$12.2M 0.04%
198,164
-318,628
-62% -$23M
CENTA icon
302
Central Garden & Pet Co Class A
CENTA
$2.39B
$12.2M 0.04%
374,991
+13,009
+4% +$415K
WGO icon
303
Winnebago Industries
WGO
$879M
$12M 0.04%
387,101
+13,588
+4% +$566K
IWO icon
304
iShares Russell 2000 Growth ETF
IWO
$14.4B
$12M 0.04%
38,173
+30,613
+405% +$10.2M
AMAT icon
305
Applied Materials
AMAT
$410B
$11.9M 0.04%
34,940
-224
-0.6% -$75.3K
CPRX
306
DELISTED
Catalyst Pharmaceutical
CPRX
$11.9M 0.04%
+479,041
New +$11.4M
MHO icon
307
M/I Homes
MHO
$3.81B
$11.6M 0.04%
+95,098
New +$12.8M
SLGN icon
308
Silgan Holdings
SLGN
$4.92B
$11.3M 0.04%
291,669
-374,746
-56% -$16.4M
OC icon
309
Owens Corning
OC
$11.6B
$11.3M 0.04%
104,472
-63,141
-38% -$7.53M
ARIS
310
Aris Mining
ARIS
$3.07B
$11.2M 0.04%
601,642
-114,825
-16% -$2.17M
WAFD icon
311
WaFd
WAFD
$2.69B
$11.1M 0.04%
352,838
-644,042
-65% -$20.7M
CLS icon
312
Celestica
CLS
$36.6B
$10.9M 0.04%
38,716
-25,569
-40% -$7.42M
PRCT icon
313
Procept Biorobotics
PRCT
$1.01B
$10.6M 0.04%
424,309
+8,066
+2% +$227K
WST icon
314
West Pharmaceutical
WST
$23.3B
$9.96M 0.03%
39,725
-1,517
-4% -$377K
MRVL icon
315
Marvell Technology
MRVL
$170B
$9.86M 0.03%
99,542
-8,887
-8% -$746K
TGB
316
Trekor Metals
TGB
$2.6B
$9.76M 0.03%
+1,513,112
New +$11M
ALK icon
317
Alaska Air
ALK
$5.3B
$9.5M 0.03%
258,191
-276,930
-52% -$13.3M
DSGX icon
318
Descartes Systems
DSGX
$6.09B
$9.17M 0.03%
128,192
-76,739
-37% -$5.66M
COR icon
319
Cencora
COR
$60.5B
$8.95M 0.03%
28,475
+4,119
+17% +$1.44M
ORCL icon
320
Oracle
ORCL
$345B
$8.2M 0.03%
55,726
-1,200,810
-96% -$195M
PSMT icon
321
Pricesmart
PSMT
$5.81B
$7.98M 0.03%
+52,991
New +$7.74M
WMT icon
322
Walmart Inc
WMT
$889B
$7.82M 0.03%
62,950
-134,259
-68% -$16.5M
QTRX icon
323
Quanterix
QTRX
$173M
$7.33M 0.02%
2,083,699
+37,250
+2% +$217K
OPLN
324
Openlane
OPLN
$4.25B
$7.1M 0.02%
243,688
-266,910
-52% -$7.7M
ISRG icon
325
Intuitive Surgical
ISRG
$128B
$6.98M 0.02%
15,142
-95
-0.6% -$48.1K
11 12
13
14 15

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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.