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William Blair Investment Management Portfolio holdings
AUM
$30.3B
1-Year Est. Return
33.75%
This Fund
S&P 500
This Quarter
Est. Return
-0.1%
1 Year Est. Return
+33.75%
3 Year Est. Return
+108.55%
5 Year Est. Return
+126.9%
10 Year Est. Return
+788.31%
AUM
$30.3B
AUM Growth
-$5.59B
(-16%)
Cap. Flow
-$4.09B
Cap. Flow
% of AUM
-13.52%
Top 10 Holdings %
Top 10 Hldgs %
30.62%
Holding
459
New
46
Increased
157
Reduced
205
Closed
46
Top Buys
| Rank | Stock | Value |
|---|---|---|
| 1 |
AstraZeneca
AZN
|
+$370M |
| 2 |
Akamai
AKAM
|
+$162M |
| 3 |
BorgWarner
BWA
|
+$152M |
| 4 |
Amphenol
APH
|
+$152M |
| 5 |
Synaptics
SYNA
|
+$129M |
Top Sells
| Rank | Stock | Value |
|---|---|---|
| 1 |
NVIDIA
NVDA
|
+$309M |
| 2 |
Sea Limited
SE
|
+$302M |
| 3 |
Amazon
AMZN
|
+$269M |
| 4 |
Microsoft
MSFT
|
+$248M |
| 5 |
Ciena
CIEN
|
+$214M |
Sector Composition
| Rank | Sector | Weight |
|---|---|---|
| 1 | Technology | 36.13% |
| 2 | Healthcare | 12.59% |
| 3 | Industrials | 11.81% |
| 4 | Financials | 11.55% |
| 5 | Consumer Discretionary | 10.11% |
| Name | Market Value | Portfolio Weight | Shares or Principal |
Change in Stake | Capital Flow | |
|---|---|---|---|---|---|---|
|
51
BorgWarner
BWA
$13.9B
| $156M | 0.52% |
+2,884,062
| New | +$152M |
|
|
52
Ciena
CIEN
$58.4B
| $155M | 0.51% |
398,579
-700,014
| -64% | -$214M |
|
|
BWIN
53
Baldwin Insurance Group
BWIN
$2.86B
| $149M | 0.49% |
6,794,492
-749,321
| -10% | -$16.2M |
|
54
Insmed
INSM
$28.6B
| $148M | 0.49% |
902,666
-318,430
| -26% | -$49M |
|
55
nVent Electric
NVT
$26.7B
| $146M | 0.48% |
1,233,874
-141,285
| -10% | -$16M |
|
56
Copart
CPRT
$27.5B
| $146M | 0.48% |
4,394,187
-191,646
| -4% | -$7.2M |
|
57
HealthEquity
HQY
$8.75B
| $139M | 0.46% |
1,659,616
-195,592
| -11% | -$16M |
|
58
Carpenter Technology
CRS
$28.4B
| $138M | 0.46% |
350,896
-66,663
| -16% | -$24.3M |
|
59
Donaldson
DCI
$11.4B
| $137M | 0.45% |
1,615,349
-92,523
| -5% | -$8.94M |
|
|
60
Amphenol
APH
$209B
| $136M | 0.45% |
+1,077,434
| New | +$152M |
|
61
Lincoln Electric
LECO
$15.4B
| $133M | 0.44% |
534,851
-74,961
| -12% | -$20.1M |
|
62
Sterling Infrastructure
STRL
$16.7B
| $132M | 0.44% |
323,421
+282,167
| +684% | +$110M |
|
63
Mercado Libre
MELI
$92.3B
| $129M | 0.43% |
74,849
-90,730
| -55% | -$175M |
|
64
Bio-Techne
TECH
$11.3B
| $129M | 0.43% |
2,462,487
+64,222
| +3% | +$3.85M |
|
65
Clean Harbors
CLH
$16.3B
| $127M | 0.42% |
443,098
+103,747
| +31% | +$28.3M |
|
66
Chipotle Mexican Grill
CMG
$41.5B
| $125M | 0.41% |
3,910,673
+597,632
| +18% | +$22.1M |
|
67
Reliance Steel & Aluminium
RS
$21.6B
| $123M | 0.41% |
403,487
+123,152
| +44% | +$39.1M |
|
68
Power Integrations
POWI
$3.61B
| $122M | 0.4% |
+2,380,677
| New | +$109M |
|
69
Eagle Materials
EXP
$6.57B
| $119M | 0.39% |
630,392
+71,648
| +13% | +$15.2M |
|
70
Dynatrace
DT
$14.2B
| $119M | 0.39% |
3,229,051
+13,198
| +0.4% | +$504K |
|
71
Bentley Systems
BSY
$10.6B
| $117M | 0.39% |
3,322,723
+707,550
| +27% | +$26M |
|
72
Glaukos
GKOS
$10.6B
| $116M | 0.38% |
1,073,819
-33,099
| -3% | -$3.72M |
|
73
First Horizon
FHN
$12.1B
| $115M | 0.38% |
5,058,092
-277,929
| -5% | -$6.65M |
|
74
SharkNinja
SN
$26.1B
| $114M | 0.38% |
1,073,384
-162,937
| -13% | -$19.1M |
|
75
Veeva Systems
VEEV
$37.4B
| $113M | 0.37% |
643,325
-237,898
| -27% | -$46.7M |
|
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William Blair Investment Management's Q1 2026 Portfolio in Review
As of Q1 2026, William Blair Investment Management held 459 positions worth $30.3B, down 16% from $35.9B the previous quarter. Its ten largest holdings account for 31% of the portfolio.
William Blair Investment Management withdrew a net $4.09B in Q1 2026, closing 46 positions and reducing 205 holdings. Its most notable exit was Sea Limited, an estimated $302M position sold in full.
By sector, the portfolio is most concentrated in Technology at 36% of assets, down from 38% a quarter earlier, followed by Healthcare and Industrials.
Against the trend, William Blair Investment Management opened a new position in Akamai worth $186M.
- William Blair Investment Management's largest Q1 2026 buy was Akamai: 1,619,060 shares worth $186M.
- William Blair Investment Management added most to AstraZeneca in Q1 2026, an estimated $370M increase.
- William Blair Investment Management's biggest Q1 2026 reduction was NVIDIA, cutting an estimated $309M.
- William Blair Investment Management fully exited Sea Limited in Q1 2026, selling an estimated $302M.
- William Blair Investment Management's ten largest holdings make up 31% of its $30.3B portfolio in Q1 2026.
- William Blair Investment Management opened 46 new positions and closed 46 in Q1 2026.
- William Blair Investment Management's portfolio value fell 16% quarter-over-quarter to $30.3B.
Based on William Blair Investment Management's 13F filing for Q1 2026, filed 8 May 2026.