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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
ATMU icon
176
Atmus Filtration Technologies
ATMU
$4.07B
$35.4M 0.1%
681,972
-69,785
-9% -$3.38M
EBC icon
177
Eastern Bankshares
EBC
$5.33B
$34.9M 0.1%
1,893,928
-194,350
-9% -$3.56M
LNTH icon
178
Lantheus
LNTH
$6.57B
$34.8M 0.1%
522,177
-52,504
-9% -$3.06M
SANM icon
179
Sanmina
SANM
$11.3B
$34.4M 0.1%
229,362
-94,656
-29% -$14M
LLY icon
180
Eli Lilly
LLY
$1.09T
$34.4M 0.1%
32,016
+16,641
+108% +$15.9M
LB
181
LandBridge Co
LB
$2.16B
$33.8M 0.09%
+690,291
New +$40.1M
SLVM icon
182
Sylvamo
SLVM
$1.54B
$33.8M 0.09%
+701,497
New +$31.9M
HURN icon
183
Huron Consulting
HURN
$2.39B
$33.6M 0.09%
194,388
-20,340
-9% -$3.33M
KEX icon
184
Kirby Corp
KEX
$7.17B
$33.5M 0.09%
304,211
-31,446
-9% -$3.2M
RNST icon
185
Renasant Corp
RNST
$3.97B
$33.4M 0.09%
948,159
+85,961
+10% +$3.05M
VCYT icon
186
Veracyte
VCYT
$3.57B
$33.3M 0.09%
790,425
+112,516
+17% +$4.54M
JCAP
187
Jefferson Capital
JCAP
$1.31B
$33.2M 0.09%
1,484,109
+89,967
+6% +$1.82M
THR
188
DELISTED
Thermon Group Holdings
THR
$33M 0.09%
887,451
-92,897
-9% -$3.05M
USLM icon
189
United States Lime & Minerals
USLM
$3.43B
$32.7M 0.09%
272,857
-60,243
-18% -$7.47M
GXO icon
190
GXO Logistics
GXO
$5.51B
$32.6M 0.09%
618,514
-42,405
-6% -$2.23M
WAFD icon
191
WaFd
WAFD
$2.79B
$31.9M 0.09%
996,880
-103,432
-9% -$3.19M
HLIO icon
192
Helios Technologies
HLIO
$2.65B
$31.4M 0.09%
587,343
-148,378
-20% -$8M
ZETA icon
193
Zeta Global
ZETA
$7.16B
$30.9M 0.09%
1,517,433
+120,636
+9% +$2.25M
KRG icon
194
Kite Realty
KRG
$5.27B
$30.8M 0.09%
1,284,604
-132,482
-9% -$3.01M
BE icon
195
Bloom Energy
BE
$70.2B
$30.3M 0.08%
+348,192
New +$36.6M
CTRE icon
196
CareTrust REIT
CTRE
$9.23B
$30.2M 0.08%
835,850
-85,482
-9% -$3.06M
ICUI icon
197
ICU Medical
ICUI
$4.48B
$30.1M 0.08%
210,766
-21,402
-9% -$2.87M
LXP icon
198
LXP Industrial Trust
LXP
$3.58B
$30M 0.08%
604,164
-63,546
-10% -$3.05M
SIGI icon
199
Selective Insurance
SIGI
$5.6B
$29.9M 0.08%
357,467
-37,394
-9% -$3M
BKV
200
BKV Corp
BKV
$2.87B
$29.9M 0.08%
1,101,386
+76,296
+7% +$1.92M
6 7
8
9 10

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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.