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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
EHC icon
101
Encompass Health
EHC
$12.3B
$97.2M 0.27%
915,920
+112,637
+14% +$13.1M
PSN icon
102
Parsons
PSN
$5.09B
$96.3M 0.27%
1,557,531
-207,088
-12% -$16.2M
BAM icon
103
Brookfield Asset Management
BAM
$87.2B
$96.1M 0.27%
1,835,120
-1,342,003
-42% -$72.1M
KRYS icon
104
Krystal Biotech
KRYS
$9.82B
$92.8M 0.26%
376,340
+227,038
+152% +$47.8M
FSV icon
105
FirstService
FSV
$6.21B
$92.7M 0.26%
596,249
+98,808
+20% +$16.1M
TPG icon
106
TPG
TPG
$8.15B
$91.7M 0.26%
1,435,749
-190,572
-12% -$11.2M
CADE
107
DELISTED
Cadence Bank
CADE
$91.6M 0.26%
2,137,482
-407,017
-16% -$16.1M
FN icon
108
Fabrinet
FN
$20.9B
$91.2M 0.25%
200,324
-26,353
-12% -$11.5M
MZTI
109
The Marzetti Company
MZTI
$3.15B
$90M 0.25%
547,629
-132,611
-19% -$22.1M
LAUR icon
110
Laureate Education
LAUR
$5.05B
$89.4M 0.25%
2,654,708
+915,358
+53% +$28.3M
VRSK icon
111
Verisk Analytics
VRSK
$23.5B
$89.4M 0.25%
+399,551
New +$90.2M
ACVA icon
112
ACV Auctions
ACVA
$1.38B
$87.4M 0.24%
10,891,686
-580,023
-5% -$4.69M
SKY icon
113
Champion Homes
SKY
$5.07B
$86.2M 0.24%
1,020,700
+15,497
+2% +$1.22M
RS icon
114
Reliance Steel & Aluminium
RS
$21.6B
$81M 0.23%
280,335
+55,532
+25% +$15.6M
VCEL icon
115
Vericel Corp
VCEL
$2.29B
$80M 0.22%
2,222,107
+11,178
+0.5% +$411K
CLH icon
116
Clean Harbors
CLH
$16.8B
$79.6M 0.22%
339,351
-45,007
-12% -$10.3M
RACE icon
117
Ferrari
RACE
$71.4B
$79.4M 0.22%
214,980
-179,469
-45% -$71.8M
MMSI icon
118
Merit Medical Systems
MMSI
$5.4B
$77.1M 0.22%
874,859
+10,863
+1% +$925K
VRRM icon
119
Verra Mobility
VRRM
$717M
$77.1M 0.22%
3,438,948
-40,500
-1% -$925K
LOPE icon
120
Grand Canyon Education
LOPE
$3.7B
$75.4M 0.21%
453,140
+334,486
+282% +$60.5M
IDA icon
121
Idacorp
IDA
$8.19B
$72.9M 0.2%
576,077
-46,980
-8% -$6.11M
FLS icon
122
Flowserve
FLS
$10.2B
$72.7M 0.2%
1,048,137
+615,769
+142% +$39.6M
GWRE icon
123
Guidewire Software
GWRE
$14.4B
$72M 0.2%
358,328
-47,622
-12% -$10.5M
MRCY icon
124
Mercury Systems
MRCY
$6.64B
$71.9M 0.2%
984,273
-1,503,684
-60% -$112M
CHRW icon
125
C.H. Robinson
CHRW
$17.3B
$70.3M 0.2%
+437,501
New +$64.6M
3 4
5
6 7

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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.