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FRONTIER CAPITAL MANAGEMENT CO LLC

Position in AMTM — Amentum Holdings, Inc.

CIK 351173 Boston, MA

Position in AMTM

as of Mar 31, 2026 · filed May 15, 2026
Position Value
$128,579,876
-$38,836,428 QoQ
Shares Held
4,930,210
-14.6% QoQ
Ownership
2.02%
of shares outstanding
% of Portfolio
1.33%
of 13F equity value
Holder Rank
not a current holder
Holding Since
Mar 2025
5 quarters on record
Voting authority Sole 55% Shared 0% None 45%

Common Shares in AMTM Over Time

Shares Held

Position Value (USD)

Position in Specialty Business Services

Industrials · as of Mar 31, 2026

FRONTIER CAPITAL MANAGEMENT CO LLC holds $158,180,800 across 3 Specialty Business Services names. AMTM ranks #1 (81.3% of the industry book) .

# Ticker Company Shares Value (USD) Open
1 AMTM
Amentum Holdings, Inc.
This page
4,930,210 $128,579,876

All Filings in AMTM

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5 filing rows on record
Report Date Value (USD) Shares
2026-03-31 $128,579,876 4,930,210
2025-12-31 $167,416,304 5,772,976
2025-09-30 $124,604,186 5,202,680
2025-06-30 $128,928,142 5,460,743
2025-03-31 $65,132,922 3,578,732