BLAIR WILLIAM & CO/IL

Diversified mechanical Mechanical CIK 902367
League rank
#124
in Diversified mechanical · #2563 overall
Long book
$34.89B
Q1 2026
Positions
1899
Top-10 weight
26%
concentration
Last quarter
+13.1%
SPY +14.8%
Turnover
12%
of book per quarter

Strategy in plain words

auto-generated from filings

BLAIR WILLIAM & CO/IL is a mechanically diversified allocator, running a $34.89B US long book across 1899 positions.

The portfolio is moderately concentrated (top 10 ≈ 26% of the book). Turnover is modest: positions are typically held for years. Current anchor positions: APPLE INC, MICROSOFT CORP, AMAZON.COM INC, NVIDIA CORP, ALPHABET INC-CL C.

Over the last 9 quarters its long book ran on average 1.8pp per quarter behind the S&P 500, beating the index in 1 of 9 quarters. Its holdings are mechanical (indexing / client flows), so position changes carry no stock-picking signal.

Implied long-book return vs S&P 500

methodology: positions priced quarterly, no shorts/options
Fund long book S&P 500
Q1 2024
-0.1%
Q2 2024
+5.7%
Q3 2024
+1.2%
Q4 2024
-3.2%
Q1 2025
+9.4%
Q2 2025
+5.0%
Q3 2025
-0.2%
Q4 2025
-6.5%
Q1 2026
+13.1%

Sector allocation

Technology
34%
Consumer discretionary
14%
Industrials
12%
Financials
11%
Healthcare
9%
Services media
8%
Other
3%
Materials
3%

Long book by quarter

$31.83B
Q1 2024
$32.42B
Q2 2024
$34.05B
Q3 2024
$34.37B
Q4 2024
$33.16B
Q1 2025
$36.00B
Q2 2025
$37.57B
Q3 2025
$37.26B
Q4 2025
$34.89B
Q1 2026

What does BLAIR WILLIAM own?

Q1 2026 13F
CompanySectorSharesValue% of bookChange
AAPL APPLE INCTechnology5.9M$1.51B4.3%-0.3%
MSFT MICROSOFT CORPTechnology3.5M$1.29B3.7%-2.1%
AMZN AMAZON.COM INCConsumer discretionary6.1M$1.26B3.6%-0.1%
NVDA NVIDIA CORPTechnology5.4M$946.6M2.7%-1.2%
GOOG ALPHABET INC-CL CTechnology3.0M$870.8M2.5%-2.7%
GOOGL ALPHABET INC-CL ATechnology2.4M$700.5M2.0%-2.3%
JPM JPMORGAN CHASE & COFinancials2.3M$678.7M1.9%-0.1%
GEV GE VERNOVA INCIndustrials664.6K$580.1M1.7%+1.9%
V VISA INC-CLASS A SHARESServices media1.8M$557.5M1.6%-4.4%
IDXX IDEXX LABORATORIES INCMaterials946.3K$531.7M1.5%-5.5%
COST COSTCO WHOLESALE CORPConsumer discretionary521.3K$519.4M1.5%0.0%
MA MASTERCARD INC - AServices media923.4K$461.4M1.3%-3.3%
META META PLATFORMS INC-CLASS ATechnology721.7K$412.9M1.2%-2.0%
FAST FASTENAL COConsumer discretionary7.4M$342.1M1.0%+5.1%
APH AMPHENOL CORP-CL ATechnology2.5M$318.4M0.9%-5.0%
LLY ELI LILLY & COHealthcare324.0K$298.0M0.9%-0.2%
WMT WALMART INCConsumer discretionary2.4M$295.1M0.8%-1.6%
BWXT BWX TECHNOLOGIES INCIndustrials1.4M$294.1M0.8%-0.1%
ABBV ABBVIE INCHealthcare1.3M$290.2M0.8%-0.3%
AVGO BROADCOM INCTechnology918.3K$284.2M0.8%+2.4%
SYK STRYKER CORPHealthcare847.7K$278.5M0.8%+0.3%
ICE INTERCONTINENTAL EXCHANGE INFinancials1.6M$250.6M0.7%-5.7%
HD HOME DEPOT INCConsumer discretionary761.4K$250.4M0.7%+0.7%
DHR DANAHER CORPTechnology1.3M$245.9M0.7%-5.5%
PGR PROGRESSIVE CORPFinancials1.2M$241.8M0.7%-13.3%
BRK/B BERKSHIRE HATHAWAY INC-CL BFinancials495.3K$237.4M0.7%+10.8%
UBER UBER TECHNOLOGIES INCServices media3.3M$237.3M0.7%-19.7%
JNJ JOHNSON & JOHNSONHealthcare955.6K$233.6M0.7%+0.6%
ECL ECOLAB INCOther866.4K$230.5M0.7%+1.0%
WSO WATSCO INCConsumer discretionary582.7K$212.0M0.6%-13.7%
AXP AMERICAN EXPRESS COFinancials693.8K$209.9M0.6%-0.9%
PANW PALO ALTO NETWORKS INCTechnology1.3M$209.2M0.6%+4.4%
ISRG INTUITIVE SURGICAL INCHealthcare425.2K$196.0M0.6%-3.2%
TDG TRANSDIGM GROUP INCIndustrials166.2K$192.7M0.6%-2.3%
NOW SERVICENOW INCTechnology1.8M$188.3M0.5%-18.7%
VEEV VEEVA SYSTEMS INC-CLASS ATechnology1.1M$187.5M0.5%-13.1%
BA BOEING CO/THEIndustrials922.1K$183.5M0.5%+35.9%
P EVERPURE INC-ATechnology2.9M$172.3M0.5%-4.4%
NFLX NETFLIX INCServices media1.8M$169.6M0.5%+17.9%
CTAS CINTAS CORPOther973.6K$164.7M0.5%-2.2%
XOM EXXON MOBIL CORPEnergy946.4K$160.6M0.5%-2.2%
CVX CHEVRON CORPEnergy716.0K$148.1M0.4%+7.4%
GWRE GUIDEWIRE SOFTWARE INCTechnology975.3K$145.9M0.4%-14.0%
ANET ARISTA NETWORKS INCTechnology1.2M$141.3M0.4%+2.4%
ABT ABBOTT LABORATORIESHealthcare1.3M$136.3M0.4%-15.8%
AON AON PLC-CLASS AFinancials421.6K$136.1M0.4%-15.1%
BX BLACKSTONE INCFinancials1.2M$135.5M0.4%-13.9%
CPRT COPART INCConsumer discretionary4.1M$135.2M0.4%-7.8%
AAON AAON INCIndustrials1.6M$134.2M0.4%-3.4%
GS GOLDMAN SACHS GROUP INCFinancials156.3K$132.2M0.4%+0.8%

13F filing history

PeriodFormFiledEntriesReported valueFlagsSource
Q1 202613F-HRMay 8, 20261922$34.90B canonicalSEC ↗
Q4 202513F-HRFeb 17, 20261920$37.26B canonicalSEC ↗
Q3 202513F-HRNov 12, 20251844$37.57B canonicalSEC ↗
Q2 202513F-HRJul 24, 20251824$36.00B canonicalSEC ↗
Q1 202513F-HRMay 9, 20251801$33.16B canonicalSEC ↗
Q4 202413F-HRFeb 12, 20251816$34.38B canonicalSEC ↗
Q3 202413F-HRNov 12, 20241821$34.05B canonicalSEC ↗
Q2 202413F-HRAug 12, 20241822$32.42B canonicalSEC ↗
Q1 202413F-HRMay 9, 20241787$31.84B canonicalSEC ↗