13F Insight
DOSSIER · 13F-HR · Q1 2026

WESTFIELD CAPITAL MANAGEMENT CO LP

$23.8B in tracked AUM across 250 positions as of Q1 2026.

WC
CIK 0001177719 · last filed Mar 31, 2026
Total AUM
$23.8B
as of Q1 2026
Holdings
250
—
positions
Whale Score
64
64
tracked
Activity
—
no data
changes this Q
AI Analysis · Q1 2026

WESTFIELD CAPITAL MANAGEMENT CO LP filed Q1 2026 13F-HR with $23.8B in disclosed U.S. equity holdings The portfolio is led by Technology exposure, with top positions including NVDA (4.6%), ASND (4.6%), FIX (3.6%). Quarter-over-quarter activity shows 15 new entries and 15 exits, with a net additive posture across 65 changed positions. Notable reduction: FIX (7.2% reduction) (COMFORT SYS USA INC).

WESTFIELD CAPITAL MANAGEMENT CO LP reports $23.8B in U.S. equity holdings for Q1 2026, anchored by a Technology-centric allocation. The top five positions by value span NVDA + ASND + FIX + AAPL + G3730V105, collectively representing a meaningful concentration within the disclosed book.

Core Holdings

  • NVDA (NVIDIA CORPORATION) — $1.1B (4.6%)
  • ASND (ASCENDIS PHARMA A/S) — $1.1B (4.6%)
  • FIX (COMFORT SYS USA INC) — $0.9B (3.6%)
  • AAPL (APPLE INC) — $0.8B (3.3%)
  • G3730V105 (FTAI AVIATION LTD) — $0.7B (2.9%)
Analysis generated by 13F Insight from SEC Form 13F filing data · Q1 2026. Methodology

Quarter at a glance — Q1 2026

Position-change comparison pending.

No quarter-over-quarter changes available.

Top 10 holdings

By portfolio weight as of Q1 2026.

#HoldingValueSharesWeight
01
NVDA
NVIDIA CORPORATION
$1.1B6.3M4.6%02
ASND
ASCENDIS PHARMA A/S
$1.1B4.8M4.6%03
FIX
COMFORT SYS USA INC
$856M621K3.6%04
AAPL
APPLE INC
$795M3.1M3.3%05
G3730V105
FTAI AVIATION LTD
$698M2.8M2.9%06
MSFT
MICROSOFT CORP
$611M1.6M2.6%07
GOOGL
ALPHABET INC
$583M2.0M2.4%08
HWM
HOWMET AEROSPACE INC
$528M2.3M2.2%09
VRT
VERTIV HOLDINGS CO
$482M1.9M2.0%10
AMZN
AMAZON COM INC
$475M2.3M2.0%

Filing history

2026Q1Mar 31
$23.8B▼ 0.7%
250 positionsView →2025Q4Dec 31
$24.0B▲ 0.7%
241 positionsView →2025Q3Sep 30
$23.8B▼ 0.0%
235 positionsView →2025Q2Jun 30
$23.8B▲ 16.0%
239 positionsLocked2025Q1Mar 31
$20.5B▼ 10.5%
244 positionsLocked2024Q4Dec 31
$23.0B▲ 3.8%
239 positionsLocked2024Q3Sep 30
$22.1B▲ 8.7%
247 positionsLocked2024Q2Jun 30
$20.4B▲ 6.9%
248 positionsLocked2024Q1Mar 31
$19.0B▲ 11.0%
244 positionsLocked2023Q4Dec 31
$17.2B▲ 16.9%
239 positionsLocked2023Q3Sep 30
$14.7B▼ 6.7%
234 positionsLocked2023Q2Jun 30
$15.7B▲ 11.2%
227 positionsLocked
Showing 12 of 82