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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
GHM icon
276
Graham Corp
GHM
$1.33B
$19.1M 0.05%
298,020
+24,005
+9% +$1.45M
ESE icon
277
ESCO Technologies
ESE
$7.78B
$19.1M 0.05%
97,783
-9,718
-9% -$2.05M
HWKN icon
278
Hawkins
HWKN
$2.7B
$19.1M 0.05%
+134,439
New +$19.8M
CLS icon
279
Celestica
CLS
$42.8B
$19M 0.05%
64,285
-53,111
-45% -$16M
LRCX icon
280
Lam Research
LRCX
$408B
$18.9M 0.05%
110,668
-1,732,948
-94% -$270M
IFS icon
281
Intercorp Financial Services
IFS
$6.09B
$18.9M 0.05%
446,887
+70,288
+19% +$2.89M
OC icon
282
Owens Corning
OC
$12.3B
$18.8M 0.05%
167,613
-11,675
-7% -$1.37M
EMBC icon
283
Embecta
EMBC
$269M
$18.6M 0.05%
1,568,414
-111,333
-7% -$1.47M
PENG
284
Penguin Solutions Inc
PENG
$3.01B
$18.3M 0.05%
+935,088
New +$20M
ESRT icon
285
Empire State Realty Trust
ESRT
$817M
$18.3M 0.05%
2,801,381
-294,369
-10% -$2.1M
NTST
286
NETSTREIT Corp
NTST
$2.08B
$18.1M 0.05%
1,028,472
-106,497
-9% -$1.94M
UMH
287
UMH Properties
UMH
$1.39B
$18M 0.05%
1,133,066
-523,736
-32% -$7.86M
VRTX icon
288
Vertex Pharmaceuticals
VRTX
$133B
$18M 0.05%
39,735
+39,139
+6,567% +$16.9M
DSGX icon
289
Descartes Systems
DSGX
$6.65B
$18M 0.05%
204,931
+53,408
+35% +$4.77M
MTDR icon
290
Matador Resources
MTDR
$6.5B
$17.7M 0.05%
416,308
-43,598
-9% -$1.83M
JBI icon
291
Janus International
JBI
$664M
$17.3M 0.05%
2,637,966
-139,274
-5% -$1.09M
ADMA icon
292
ADMA Biologics
ADMA
$2.19B
$16.2M 0.05%
+890,861
New +$15M
PAY icon
293
Paymentus
PAY
$5.08B
$16.1M 0.05%
+510,498
New +$16.6M
SHO icon
294
Sunstone Hotel Investors
SHO
$2.01B
$16.1M 0.04%
1,797,874
-188,421
-9% -$1.73M
STEL
295
DELISTED
Stellar Bancorp
STEL
$15.9M 0.04%
514,630
-640,315
-55% -$19.7M
OPLN
296
Openlane
OPLN
$4.34B
$15.2M 0.04%
510,598
-608,087
-54% -$16.4M
WGO icon
297
Winnebago Industries
WGO
$915M
$15.1M 0.04%
373,513
-39,569
-10% -$1.44M
EFSC icon
298
Enterprise Financial Services Corp
EFSC
$2.41B
$13.3M 0.04%
246,029
-331,936
-57% -$18.2M
PRCT icon
299
Procept Biorobotics
PRCT
$1.22B
$13.1M 0.04%
416,243
+33,226
+9% +$1.1M
QTRX icon
300
Quanterix
QTRX
$139M
$13M 0.04%
2,046,449
+731,169
+56% +$4.54M
10 11
12
13 14

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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.