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William Blair & Company

William Blair & Company Portfolio holdings

AUM $34.9B
1-Year Est. Return 18.88%
This Fund
S&P 500
This Quarter Est. Return
+1.73%
1 Year Est. Return
+18.88%
3 Year Est. Return
+73.84%
5 Year Est. Return
+90.13%
10 Year Est. Return
+563.35%
AUM
$37.3B
AUM Growth
-$310M
Cap. Flow
-$212M
Cap. Flow %
-0.57%
Top 10 Hldgs %
27.41%
Holding
1,963
New
120
Increased
759
Reduced
753
Closed
96

Top Buys

Rank Stock Value
1
BWXT icon
BWX Technologies
BWXT
+$46.6M
2
META icon
Meta Platforms (Facebook)
META
+$38.3M
3
NOW icon
ServiceNow
NOW
+$37.6M
4
VEU icon
Vanguard FTSE All-World ex-US ETF
VEU
+$32.4M
5
GLD icon
SPDR Gold Trust
GLD
+$29.4M

Top Sells

Rank Stock Value
1
FISV
Fiserv Inc
FISV
+$114M
2
CSGP icon
CoStar Group
CSGP
+$78.3M
3
CWAN
Clearwater Analytics
CWAN
+$75.3M
4
POOL icon
Pool Corp
POOL
+$54M
5
ZTS icon
Zoetis
ZTS
+$51.3M

Sector Composition

Rank Sector Weight
1 Technology 25.8%
2 Financials 13.4%
3 Industrials 12.04%
4 Healthcare 11.22%
5 Communication Services 7.63%
Name Market Value Portfolio Weight Shares or Principal Change
in Stake 		Capital Flow
AMD icon
151
Advanced Micro Devices
AMD
$789B
$43.3M 0.12%
202,018
-6,844
-3% -$1.54M
IJH icon
152
iShares Core S&P Mid-Cap ETF
IJH
$127B
$43.1M 0.12%
652,965
+1,970
+0.3% +$129K
MRVL icon
153
Marvell Technology
MRVL
$196B
$42.1M 0.11%
495,078
+37,469
+8% +$3.28M
GNRC icon
154
Generac Holdings
GNRC
$12.5B
$41.7M 0.11%
305,649
+63,499
+26% +$10.2M
IJR icon
155
iShares Core S&P Small-Cap ETF
IJR
$112B
$41.4M 0.11%
344,144
+65,643
+24% +$7.85M
DIS icon
156
Walt Disney
DIS
$181B
$40.6M 0.11%
356,651
-61,160
-15% -$6.74M
CME icon
157
CME Group
CME
$94.8B
$40.4M 0.11%
147,840
+1,208
+0.8% +$328K
SPMD icon
158
State Street SPDR Portfolio S&P 400 Mid Cap ETF
SPMD
$18.9B
$40M 0.11%
691,040
+14,100
+2% +$810K
PM icon
159
Philip Morris
PM
$295B
$39.8M 0.11%
248,397
-29,163
-11% -$4.52M
NET icon
160
Cloudflare
NET
$107B
$39M 0.1%
197,860
-4,274
-2% -$904K
KLAC icon
161
KLA
KLAC
$259B
$38.7M 0.1%
318,540
+5,840
+2% +$685K
FISV
162
Fiserv Inc
FISV
$27.9B
$38.2M 0.1%
568,584
-1,366,438
-71% -$114M
VO icon
163
Vanguard Morningstar Mid-Cap ETF
VO
$109B
$37.4M 0.1%
515,136
+14,320
+3% +$1.04M
PODD icon
164
Insulet
PODD
$9.79B
$37.4M 0.1%
131,434
-11,939
-8% -$3.73M
EPD icon
165
Enterprise Products Partners
EPD
$81.7B
$37M 0.1%
1,153,901
+58,152
+5% +$1.84M
TSM icon
166
TSMC
TSM
$2.18T
$36.9M 0.1%
121,329
+25,281
+26% +$7.42M
SMMD icon
167
iShares Russell 2500 ETF
SMMD
$3.75B
$36M 0.1%
479,957
+292,966
+157% +$21.8M
XLF icon
168
State Street Financial Select Sector SPDR ETF
XLF
$58.8B
$35M 0.09%
639,864
+85,712
+15% +$4.57M
PLTR icon
169
Palantir
PLTR
$413B
$35M 0.09%
196,704
+23,708
+14% +$4.29M
PFE icon
170
Pfizer
PFE
$153B
$34.4M 0.09%
1,382,669
-38,344
-3% -$967K
UNH icon
171
UnitedHealth
UNH
$370B
$34M 0.09%
102,862
-29,276
-22% -$9.92M
PWR icon
172
Quanta Services
PWR
$101B
$33.9M 0.09%
80,301
+40,956
+104% +$18M
VWO icon
173
Vanguard FTSE Emerging Markets ETF
VWO
$126B
$33.8M 0.09%
629,358
+25,532
+4% +$1.39M
TWLO icon
174
Twilio
TWLO
$36.6B
$33.6M 0.09%
235,993
+36,425
+18% +$4.51M
IAU icon
175
iShares Gold Trust
IAU
$64.4B
$33.1M 0.09%
407,453
+42,102
+12% +$3.29M
5 6
7
8 9

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William Blair & Company's Q4 2025 Portfolio in Review

As of Q4 2025, William Blair & Company held 1,963 positions worth $37.3B, down 0.82% from $37.6B the previous quarter. Its ten largest holdings account for 27% of the portfolio.

William Blair & Company's Q4 2025 filing shows 120 new, 759 increased, 753 reduced and 96 closed positions. Its largest new stake was Wingstop: 90,773 shares worth $21.6M. The largest sale was Fiserv Inc, an estimated $114M.

By sector, the portfolio is most concentrated in Technology at 26% of assets, down from 27% a quarter earlier, followed by Financials and Industrials.

  • William Blair & Company's largest Q4 2025 buy was Wingstop: 90,773 shares worth $21.6M.
  • William Blair & Company added most to BWX Technologies in Q4 2025, an estimated $46.6M increase.
  • William Blair & Company's biggest Q4 2025 reduction was Fiserv Inc, cutting an estimated $114M.
  • William Blair & Company fully exited SAP in Q4 2025, selling an estimated $9.19M.
  • William Blair & Company's ten largest holdings make up 27% of its $37.3B portfolio in Q4 2025.
  • William Blair & Company opened 120 new positions and closed 96 in Q4 2025.
  • William Blair & Company's portfolio value fell 0.82% quarter-over-quarter to $37.3B.

Based on William Blair & Company's 13F filing for Q4 2025, filed 17 Feb 2026.