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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 | |
|---|---|---|---|---|---|---|
26
TransUnion
TRU
$15.3B
| $200M | 0.66% |
2,891,187
-1,074,308
| -27% | -$82.2M |
|
27
Onto Innovation
ONTO
$15.3B
| $198M | 0.65% |
964,213
-762,374
| -44% | -$156M |
|
28
Idexx Laboratories
IDXX
$46.2B
| $198M | 0.65% |
351,621
-89,703
| -20% | -$57.5M |
|
29
Nextpower Inc
NXT
$15.7B
| $196M | 0.65% |
1,622,489
+259,695
| +19% | +$28.8M |
|
30
argenx
ARGX
$54.1B
| $194M | 0.64% |
266,067
+42,401
| +19% | +$33.2M |
|
31
CAVA Group
CAVA
$7.27B
| $194M | 0.64% |
2,393,971
-25,276
| -1% | -$1.84M |
|
32
Lattice Semiconductor
LSCC
$18.5B
| $190M | 0.63% |
2,043,720
-81,540
| -4% | -$7.31M |
|
33
F5
FFIV
$22.7B
| $188M | 0.62% |
649,948
+99,684
| +18% | +$27.6M |
|
|
34
Akamai
AKAM
$15.9B
| $186M | 0.61% |
+1,619,060
| New | +$162M |
|
35
Cameco
CCJ
$42.4B
| $183M | 0.6% |
1,682,303
-298,524
| -15% | -$34.2M |
|
36
UnitedHealth
UNH
$370B
| $182M | 0.6% |
673,263
-88,980
| -12% | -$26.5M |
|
37
Madrigal Pharmaceuticals
MDGL
$11.8B
| $178M | 0.59% |
340,519
-13,701
| -4% | -$6.55M |
|
38
Nu Holdings
NU
$66.9B
| $176M | 0.58% |
12,267,600
-6,431,767
| -34% | -$104M |
|
39
Globus Medical
GMED
$11.2B
| $173M | 0.57% |
2,009,763
-510,019
| -20% | -$45.8M |
|
40
C.H. Robinson
CHRW
$17.5B
| $173M | 0.57% |
1,041,658
+604,157
| +138% | +$108M |
|
|
P
41
Everpure Inc
P
$29.9B
| $170M | 0.56% |
2,881,481
-861,447
| -23% | -$58.3M |
|
42
Snowflake
SNOW
$115B
| $170M | 0.56% |
1,127,525
-219,473
| -16% | -$40.6M |
|
|
TLN
43
Talen Energy Corp
TLN
$16.7B
| $168M | 0.55% |
525,214
-44,185
| -8% | -$15.6M |
|
44
Grand Canyon Education
LOPE
$3.98B
| $167M | 0.55% |
979,734
+526,594
| +116% | +$88.3M |
|
45
Everest Group
EG
$14.4B
| $165M | 0.55% |
506,166
-78,135
| -13% | -$25.7M |
|
46
Halozyme
HALO
$12.2B
| $163M | 0.54% |
2,525,975
+683,019
| +37% | +$48.1M |
|
47
Martin Marietta Materials
MLM
$33B
| $160M | 0.53% |
272,392
+2,189
| +0.8% | +$1.4M |
|
48
Coherent
COHR
$74.2B
| $159M | 0.53% |
668,137
-204,923
| -23% | -$46.9M |
|
49
Curtiss-Wright
CW
$25.5B
| $158M | 0.52% |
232,069
-45,768
| -16% | -$30.4M |
|
50
Regal Rexnord
RRX
$11.9B
| $157M | 0.52% |
837,493
+78,210
| +10% | +$14.5M |
|
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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.