13F INSTITUTION · CIK 0001177719 · 2026-Q2 · filed Aug 12, 2026

Westfield Capital Management Co

WESTFIELD CAPITAL MANAGEMENT CO LP
$30.6B
13F long value · 2026-Q2
Positions278
CategoryAsset Manager
Quarters tracked8
● #260 of 581 by 13F value
Size rank 6/10
51 NEW33 ADD17 2×+31 TRIM9 NEAR EXIT21 EXIT
Snapshot
Westfield Capital Management Co's 13F portfolio at a glance — size, concentration and this quarter's activity.
13F value (AUM)
$30.6B
Positions
278 (23 unmapped)
Top 100 weight
79.8%
Quarters tracked
8
Latest 13F filed
Aug 12, 2026
New positions
51
Exits / near-exits
30
13F value by quarter
Total reported long value each quarter — fund flows plus market moves.
$22.1B
2024-Q3
$23.0B
2024-Q4
$20.5B
2025-Q1
$23.8B
2025-Q2
$23.8B
2025-Q3
$24.0B
2025-Q4
$23.8B
2026-Q1
$30.6B
2026-Q2
Top holdings — 2026-Q2
The fund's largest reported positions. The 100 shown cover 79.8% of the portfolio.
TickerIssuerWeightValueSharesSince 2026-Q2
NVDA NVIDIA CORPORATION5.3%$1.6B8.1M+18.0%
GOOGL ALPHABET INC4.4%$1.3B3.7M-4.0%
— ASCENDIS PHARMA A/S4.2%$1.3B4.8M—
AXON AXON ENTERPRISE INC2.7%$836.1M1.5M-28.2%
— FTAI AVIATION LTD2.6%$794.6M2.9M—
AAPL APPLE INC2.4%$744.7M2.6M+14.9%
FIX COMFORT SYS USA INC2.3%$704.5M355.4K-9.5%
AVGO BROADCOM INC1.9%$588.0M1.6M-7.6%
MSFT MICROSOFT CORP1.7%$527.6M1.4M+39.3%
HWM HOWMET AEROSPACE INC1.7%$516.6M1.9M-10.1%
LLY ELI LILLY & CO1.6%$499.8M416.7K-27.6%
SNOW SNOWFLAKE INC1.4%$441.9M1.7M-43.3%
MKSI MKS INC.1.3%$413.0M928.6K-37.4%
META META PLATFORMS INC1.2%$381.6M677.4K+29.9%
VRT VERTIV HOLDINGS CO1.2%$353.0M1.1M-3.7%
Quarterly changes — 2026-Q2
What Westfield Capital Management Co opened, added, trimmed and exited this quarter, largest dollar moves first.
ActionTickerIssuerPrev sharesCurr sharesChangeValue Δ
NEW—ASCENDIS PHARMA A/S—4.8M—+$1.3B
EXIT—ASCENDIS PHARMA A/S4.8M0-100.0%-$1.1B
ADDGOOGLALPHABET INC2.0M3.7M+85.0%+$757.0M
ADDNVDANVIDIA CORPORATION6.3M8.1M+27.9%+$515.0M
ADDAXONAXON ENTERPRISE INC1.1M1.5M+40.2%+$384.2M
2×+SNOWSNOWFLAKE INC718.8K1.7M+141.6%+$333.5M
TRIMAMZNAMAZON COM INC2.3M859.8K-62.3%-$269.9M
2×+AMDADVANCED MICRO DEVICES INC5.0K403.1K+7929.5%+$233.1M
2×+MUMICRON TECHNOLOGY INC100.4K228.2K+127.2%+$229.5M
ADDAVGOBROADCOM INC1.2M1.6M+25.8%+$205.1M
Conviction over time
Portfolio weight of the current top long holdings, quarter by quarter — rising weight = growing conviction.
NVDA 5.3%
GOOGL 4.4%
AXON 2.7%
AAPL 2.4%
FIX 2.3%
AVGO 1.9%
MSFT 1.7%
HWM 1.7%