Arkolith/Funds/Westfield Capital Management Co LP

Westfield Capital Management Co LP

CIK 1177719Asset manager
Holdings as of Jun 30, 2026·disclosed Aug 12, 2026·~43-day 13F lag·13F-HR
Active Filer

Westfield Capital Management Co LP holds a diversified book of 278 stocks worth $30.6B as of Q2 2026 (disclosed Aug 12, 2026, a ~43-day 13F lag). This quarter they opened Ascendis Pharma A/s and trimmed Apple Inc. Their largest long position is Nvidia Corp at 5% of the equity book.

Opened
102
bought for the first time
Added to
98
already held, bought more
Trimmed
103
sold some, still holds it
Sold out
41
exited the position entirely

Concentration

Top-heavy: diversified book

Top 5 holdings
19%
Top 10 holdings
29%
Top 20 holdings
40%

Share of the disclosed book in its largest positions. A higher top-5 share means a more concentrated, higher-conviction portfolio.

Direct sector allocation

100% mapped to company sectors

Information Technology
42%
Industrials
18%
Health Care
16%
Financials
7%
Consumer Discretionary
6%
Materials
5%
Utilities
2%
Communication Services
1%

Direct operating-company sectors from our SIC-based security master. ETF/fund and unclassified holdings stay visible separately; this is not ETF look-through exposure.

Biggest moves: latest quarter

Estimated $ traded · quarter-end prices, no cost basis

Bought
Trimmed / exited

Funds with the most overlap

Other tracked managers holding the same core names as Westfield Capital Management Co LP

Manager / fundShared namesTheir $ in those
GEODE CAPITAL MANAGEMENT, LLC80 / 80$704.4B
Arax Advisory Partners80 / 80$2.2B
Clearstead Advisors, LLC80 / 80$1.5B
GAMMA Investing LLC80 / 80$838.5M
BlackRock, Inc.79 / 80$1.8T
STATE STREET CORP79 / 80$1.2T
FMR LLC79 / 80$760.6B
MORGAN STANLEY79 / 80$389.6B

Ranked by how many of Westfield Capital Management Co LP's top 80 disclosed names each fund also holds: a cross-fund conviction signal from the latest 13F of every tracked manager.

Holdings: largest first

Bars show each stock's share of the portfolio. Click a row for its position history.

278 positions
#SecurityValueShares% PortLast moveHistory
1Nvidia Corporation
COM
$1.6B8.08M
5.3%
▲+28%
Added · +1.8M sh
2Alphabet Inc
CAP STK CL A
$1.3B3.75M
4.4%
▲+85%
Added · +1.7M sh
3Ascendis Pharma A/s
ORD SHS
$1.3B4.80M
4.2%
▲New
New position
4Axon Enterprise Inc
COM
$836.1M1.49M
2.7%
▲+40%
Added · +427K sh
5Ftai Aviation Ltd
SHS
$794.6M2.94M
2.6%
▲+3.1%
Added · +89K sh
6Apple Inc
COM
$744.7M2.57M
2.4%
▼−18%
Reduced · −559K sh
7Comfort Sys USA Inc
COM
$704.5M355.4K
2.3%
▼−43%
Reduced · −265K sh
8Broadcom Inc
COM
$588.0M1.56M
1.9%
▲+26%
Added · +320K sh
9Microsoft Corp
COM
$527.6M1.41M
1.7%
▼−14%
Reduced · −235K sh
10Howmet Aerospace Inc
COM
$516.6M1.92M
1.7%
▼−16%
Reduced · −368K sh
11Eli Lilly & Co
COM
$499.8M416.7K
1.6%
▲+14%
Added · +52K sh
12Snowflake Inc
COM SHS
$441.9M1.74M
1.4%
▲+142%
Added · +1.0M sh
13MKS Inc.
COM
$413.0M928.6K
1.3%
▼−11%
Reduced · −118K sh
14Meta Platforms Inc
CL A
$381.6M677.4K
1.2%
▲+29%
Added · +151K sh
15Vertiv Holdings Co
COM CL A
$353.0M1.05M
1.2%
▼−45%
Reduced · −867K sh
16Ge Vernova Inc
COM
$283.5M241.3K
0.9%
▲+21%
Added · +42K sh
17Micron Technology Inc
COM
$263.4M228.2K
0.9%
▲+127%
Added · +128K sh
18Visa Inc
COM CL A
$261.6M762.4K
0.9%
▲+67%
Added · +306K sh
19Api Group Corp
COM STK
$260.6M6.15M
0.9%
▲+33%
Added · +1.5M sh
20Tapestry Inc
COM
$248.3M1.70M
0.8%
▼−23%
Reduced · −502K sh
21Rhythm Pharmaceuticals Inc
COM
$245.2M2.21M
0.8%
▲+14%
Added · +279K sh
22Life Time Group Holdings Inc
COMMON STOCK
$244.8M6.00M
0.8%
▲+88%
Added · +2.8M sh
23Taiwan Semiconductor Manufac
SPONSORED ADS
$244.0M511.0K
0.8%
▲+3.5%
Added · +17K sh
24Guardant Health Inc
COM
$243.7M1.62M
0.8%
▲+19%
Added · +262K sh
25Quanta Svcs Inc
COM
$238.7M331.5K
0.8%
▼−0.1%
Reduced · −327 sh
26Servicenow Inc
COM
$235.7M2.37M
0.8%
▲+70%
Added · +980K sh
27Advanced Micro Devices Inc
COM
$234.2M403.1K
0.8%
▲80×
Added · +398K sh
28Palo Alto Networks Inc
COM
$224.5M658.3K
0.7%
▲+3.4%
Added · +22K sh
29Woodward Inc
COM
$224.0M526.5K
0.7%
▲+93%
Added · +254K sh
30Arista Networks Inc
COM SHS
$223.7M1.32M
0.7%
▲+69%
Added · +537K sh
31LPL Finl Hldgs Inc
COM
$223.4M793.1K
0.7%
▼−10%
Reduced · −88K sh
32Rocket Lab Corp
COM
$214.9M2.11M
0.7%
▼−33%
Reduced · −1.1M sh
33Amer Sports Inc
COM SHS
$214.7M6.34M
0.7%
▲+61%
Added · +2.4M sh
34Cloudflare Inc
CL A COM
$204.9M835.5K
0.7%
▲+54%
Added · +294K sh
35Amazon Com Inc
COM
$204.9M859.8K
0.7%
▼−62%
Reduced · −1.4M sh
36Garmin Ltd
SHS
$204.5M861.1K
0.7%
▲+129%
Added · +485K sh
37Regal Rexnord Corporation
COM
$204.1M857.0K
0.7%
▲+26%
Added · +175K sh
38Natera Inc
COM
$197.2M726.6K
0.6%
▼−3.7%
Reduced · −28K sh
39Morgan Stanley
COM NEW
$196.6M940.6K
0.6%
▲+89%
Added · +444K sh
40Carpenter Technology Corp
COM
$193.7M314.1K
0.6%
▲New
New position
41Samsara Inc
COM CL A
$189.3M5.84M
0.6%
▲+15%
Added · +764K sh
42Dynatrace Inc
COM NEW
$186.6M4.25M
0.6%
▲+0.9%
Added · +40K sh
43Caterpillar Inc
COM
$186.0M174.6K
0.6%
▲+440%
Added · +142K sh
44Semtech Corp
COM
$183.4M1.13M
0.6%
▼−12%
Reduced · −147K sh
45Ametek Inc
COM
$175.1M723.8K
0.6%
▼−3.0%
Reduced · −22K sh
46Abivax Sa
SPONSORED ADS
$174.5M1.31M
0.6%
▼−1.0%
Reduced · −13K sh
47Insmed Inc
COM PAR $.01
$173.7M1.63M
0.6%
▲+11%
Added · +161K sh
48Itt Inc
COM
$164.2M830.4K
0.5%
▲+18%
Added · +127K sh
49Gilead Sciences Inc
COM
$162.7M1.29M
0.5%
▲48×
Added · +1.3M sh
50PTC Therapeutics Inc
COM
$159.6M1.96M
0.5%
▲New
New position
Showing 50 of 278 positions
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Filing history

As-of date vs the date the SEC received each filing

QuarterAs ofFiledPositionsValueForm
Q2 2026Jun 30, 2026Aug 12, 2026278$30.6B13F-HR
Q1 2026Mar 31, 2026May 11, 2026250$23.8B13F-HR
Q4 2025Dec 31, 2025Feb 11, 2026241$24.0B13F-HR
Q3 2025Sep 30, 2025Nov 12, 2025235$23.8B13F-HR
Q2 2025Jun 30, 2025Aug 12, 2025239$23.8B13F-HR
Q1 2025Mar 31, 2025May 9, 2025244$20.5B13F-HR
Q4 2024Dec 31, 2024Feb 11, 2025239$23.0B13F-HR
Q3 2024Sep 30, 2024Nov 12, 2024247$22.1B13F-HR
Q2 2024Jun 30, 2024Aug 14, 2024248$20.4B13F-HR
Q1 2024Mar 31, 2024May 10, 2024244$19.0B13F-HR
Q4 2023Dec 31, 2023Feb 9, 2024239$17.2B13F-HR
Q3 2023Sep 30, 2023Nov 13, 2023234$14.7B13F-HR
Q2 2023Jun 30, 2023Aug 11, 2023227$15.7B13F-HR
Q1 2023Mar 31, 2023May 12, 2023222$14.2B13F-HR
Q4 2022Dec 31, 2022Feb 13, 2023226$13.0B13F-HR
Q3 2022Sep 30, 2022Nov 14, 2022230$12.6B13F-HR
Q2 2022Jun 30, 2022Aug 12, 2022235$12.7B13F-HR
Q1 2022Mar 31, 2022May 16, 2022235$15.6B13F-HR
Q4 2021Dec 31, 2021Feb 10, 2022244$16.8B13F-HR
Q3 2021Sep 30, 2021Nov 12, 2021235$16.6B13F-HR
Q2 2021Jun 30, 2021Aug 10, 2021241$16.7B13F-HR
Q1 2021Mar 31, 2021May 14, 2021243$16.1B13F-HR
Q4 2020Dec 31, 2020Feb 12, 2021247$16.9B13F-HR
Q3 2020Sep 30, 2020Nov 13, 2020235$15.4B13F-HR

Data source

Holdings from SEC EDGAR 13F-HR filings, updated quarterly, filed up to 45 days after quarter-end. Public domain. The book and weighting are long equity only; disclosed put/call options are listed separately and excluded from those totals. Price-derived performance is withheld until the price-source policy and freshness gate are green.