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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
INVX
301
Innovex International
INVX
$2.13B
$12.8M 0.04%
585,375
-77,074
-12% -$1.61M
STRL icon
302
Sterling Infrastructure
STRL
$16.8B
$12.6M 0.04%
41,254
-36,836
-47% -$12.7M
ASR icon
303
Grupo Aeroportuario del Sureste
ASR
$8.24B
$12.5M 0.04%
38,754
-4,158
-10% -$1.29M
RUSHA icon
304
Rush Enterprises Class A
RUSHA
$9.41B
$12.5M 0.03%
231,342
-762,325
-77% -$39.6M
HDB icon
305
HDFC Bank
HDB
$119B
$12.4M 0.03%
338,403
-101,150
-23% -$3.64M
AAMI
306
Acadian Asset Management
AAMI
$3.27B
$12M 0.03%
255,086
-26,232
-9% -$1.21M
ARIS
307
Aris Mining
ARIS
$3.66B
$11.6M 0.03%
+716,467
New +$8.81M
DXCM icon
308
DexCom
DXCM
$34.3B
$11.4M 0.03%
+171,573
New +$11.1M
WST icon
309
West Pharmaceutical
WST
$24.8B
$11.3M 0.03%
41,242
+437
+1% +$120K
EPC icon
310
Edgewell Personal Care
EPC
$1.32B
$11.3M 0.03%
663,455
-70,434
-10% -$1.3M
HUM icon
311
Humana
HUM
$46.7B
$11.2M 0.03%
43,877
+5,382
+14% +$1.41M
TTE icon
312
TotalEnergies
TTE
$194B
$10.8M 0.03%
+164,875
New +$10.4M
CENTA icon
313
Central Garden & Pet Co Class A
CENTA
$2.43B
$10.6M 0.03%
361,982
-522,802
-59% -$15.1M
TITN icon
314
Titan Machinery
TITN
$431M
$10.5M 0.03%
695,104
-74,931
-10% -$1.21M
ATAT icon
315
Atour Lifestyle Holdings
ATAT
$4.6B
$10.1M 0.03%
255,330
+65,849
+35% +$2.58M
AEHR icon
316
Aehr Test Systems
AEHR
$4.22B
$10M 0.03%
495,672
-398,389
-45% -$9.64M
XP icon
317
XP
XP
$7.98B
$9.77M 0.03%
596,760
-1,255,837
-68% -$22.1M
IIIV icon
318
i3 Verticals
IIIV
$323M
$9.73M 0.03%
+386,385
New +$10.9M
MRVL icon
319
Marvell Technology
MRVL
$195B
$9.21M 0.03%
108,429
+89,755
+481% +$7.86M
AMAT icon
320
Applied Materials
AMAT
$435B
$9.04M 0.03%
35,164
-9,336
-21% -$2.24M
AL
321
DELISTED
Air Lease Corp
AL
$8.95M 0.03%
139,279
-209,026
-60% -$13.3M
CRH icon
322
CRH
CRH
$65.2B
$8.74M 0.02%
70,051
-30,667
-30% -$3.65M
ISRG icon
323
Intuitive Surgical
ISRG
$142B
$8.63M 0.02%
15,237
-6,835
-31% -$3.64M
CLBT icon
324
Cellebrite
CLBT
$3.8B
$8.55M 0.02%
474,015
-8,802
-2% -$158K
COR icon
325
Cencora
COR
$60B
$8.23M 0.02%
24,356
-10,549
-30% -$3.6M
11 12
13
14 15

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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.