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William Blair Investment Management

William Blair Investment Management Portfolio holdings

AUM $33.3B
1-Year Est. Return 44.76%
This Fund
S&P 500
This Quarter Est. Return
+3.11%
1 Year Est. Return
+44.76%
3 Year Est. Return
+140.8%
5 Year Est. Return
+166.51%
10 Year Est. Return
+978.6%
AUM
$35.9B
AUM Growth
-$2.82B
Cap. Flow
-$3B
Cap. Flow %
-8.37%
Top 10 Hldgs %
32.55%
Holding
459
New
45
Increased
106
Reduced
259
Closed
46

Top Buys

Rank Stock Value
1
SNOW icon
Snowflake
SNOW
+$202M
2
ARGX icon
argenx
ARGX
+$191M
3
GOOGL icon
Alphabet (Google) Class A
GOOGL
+$191M
4
HQY icon
HealthEquity
HQY
+$178M
5
FFIV icon
F5
FFIV
+$148M

Top Sells

Rank Stock Value
1
LRCX icon
Lam Research
LRCX
+$270M
2
CIEN icon
Ciena
CIEN
+$260M
3
UBER icon
Uber
UBER
+$233M
4
LYV icon
Live Nation Entertainment
LYV
+$229M
5
LRN icon
Stride
LRN
+$225M

Sector Composition

Rank Sector Weight
1 Technology 37.93%
2 Financials 12.94%
3 Healthcare 12.67%
4 Consumer Discretionary 10.8%
5 Industrials 9.43%
Name Market Value Portfolio Weight Shares or Principal Change
in Stake 		Capital Flow
HQY icon
51
HealthEquity
HQY
$8.69B
$170M 0.47%
+1,855,208
New +$178M
MLM icon
52
Martin Marietta Materials
MLM
$32.8B
$168M 0.47%
270,203
-7,153
-3% -$4.45M
COHR icon
53
Coherent
COHR
$67.3B
$161M 0.45%
873,060
-491,957
-36% -$73.6M
PLNT icon
54
Planet Fitness
PLNT
$3.62B
$158M 0.44%
1,459,295
-134,612
-8% -$13.9M
LSCC icon
55
Lattice Semiconductor
LSCC
$18.5B
$156M 0.44%
2,125,260
+731,568
+52% +$52.1M
CW icon
56
Curtiss-Wright
CW
$26.6B
$153M 0.43%
277,837
-32,255
-10% -$18M
DCI icon
57
Donaldson
DCI
$11.2B
$151M 0.42%
1,707,872
+1,701,387
+26,236% +$148M
FOLD
58
DELISTED
Amicus Therapeutics
FOLD
$151M 0.42%
10,627,717
-5,121,523
-33% -$50.3M
APPF icon
59
AppFolio
APPF
$7.04B
$148M 0.41%
638,241
+86,272
+16% +$20.5M
CHE icon
60
Chemed
CHE
$6.97B
$148M 0.41%
344,807
-40,317
-10% -$17.6M
LECO icon
61
Lincoln Electric
LECO
$15.5B
$146M 0.41%
+609,812
New +$144M
WAL icon
62
Western Alliance Bancorporation
WAL
$8.93B
$144M 0.4%
1,711,503
-683,219
-29% -$55.5M
CWST icon
63
Casella Waste Systems
CWST
$5.88B
$144M 0.4%
1,468,206
-341,661
-19% -$31.7M
CAVA icon
64
CAVA Group
CAVA
$7.95B
$142M 0.4%
2,419,247
+530,524
+28% +$29.6M
CWAN
65
DELISTED
Clearwater Analytics
CWAN
$142M 0.4%
5,880,506
-2,695,866
-31% -$54M
TECH icon
66
Bio-Techne
TECH
$11.2B
$141M 0.39%
2,398,265
+688,603
+40% +$41.8M
FFIV icon
67
F5
FFIV
$23.7B
$140M 0.39%
+550,264
New +$148M
NVT icon
68
nVent Electric
NVT
$27.9B
$140M 0.39%
1,375,159
-1,025,220
-43% -$106M
DT icon
69
Dynatrace
DT
$14.3B
$139M 0.39%
3,215,853
-181,985
-5% -$8.48M
SN icon
70
SharkNinja
SN
$25.9B
$138M 0.39%
1,236,321
-145,130
-11% -$14.3M
ONB icon
71
Old National Bancorp
ONB
$10.3B
$133M 0.37%
5,957,936
+88,096
+2% +$1.9M
TER icon
72
Teradyne
TER
$63.5B
$133M 0.37%
684,578
-90,885
-12% -$15.6M
CRS icon
73
Carpenter Technology
CRS
$26.9B
$131M 0.37%
417,559
-48,685
-10% -$14.6M
CHDN icon
74
Churchill Downs
CHDN
$6.14B
$130M 0.36%
1,145,413
+127,687
+13% +$13.2M
SPOT icon
75
Spotify
SPOT
$101B
$129M 0.36%
221,748
-60,576
-21% -$37.9M
1 2
3
4 5

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William Blair Investment Management's Q4 2025 Portfolio in Review

As of Q4 2025, William Blair Investment Management held 459 positions worth $35.9B, down 7.3% from $38.7B the previous quarter. Its ten largest holdings account for 33% of the portfolio.

William Blair Investment Management withdrew a net $3B in Q4 2025, closing 46 positions and reducing 259 holdings. Its most notable exit was Live Nation Entertainment, an estimated $229M position sold in full.

By sector, the portfolio is most concentrated in Technology at 38% of assets, down from 39% a quarter earlier, followed by Financials and Healthcare.

Against the trend, William Blair Investment Management opened a new position in argenx worth $188M.

  • William Blair Investment Management's largest Q4 2025 buy was argenx: 223,666 shares worth $188M.
  • William Blair Investment Management added most to Snowflake in Q4 2025, an estimated $202M increase.
  • William Blair Investment Management's biggest Q4 2025 reduction was Lam Research, cutting an estimated $270M.
  • William Blair Investment Management fully exited Live Nation Entertainment in Q4 2025, selling an estimated $229M.
  • William Blair Investment Management's ten largest holdings make up 33% of its $35.9B portfolio in Q4 2025.
  • William Blair Investment Management opened 45 new positions and closed 46 in Q4 2025.
  • William Blair Investment Management's portfolio value fell 7.3% quarter-over-quarter to $35.9B.

Based on William Blair Investment Management's 13F filing for Q4 2025, filed 9 Feb 2026.