FRONTIER CAPITAL MANAGEMENT CO LLC

Position in AMTM — Amentum Holdings, Inc.

CIK 351173 Boston, MA

Position in AMTM

as of Jun 30, 2026 · filed Aug 14, 2026 Compact

Position Value

$85,655,880

-$42,923,996 QoQ

Shares Held

4,143,971

-15.9% QoQ

Ownership

1.69%

of shares outstanding

% of Portfolio

0.80%

of 13F equity value

Holder Rank

#11

of 462 holders

Holding Since

Mar 2025

6 quarters on record

Voting authority Sole 54% Shared 0% None 46%

Industrials · as of Jun 30, 2026

FRONTIER CAPITAL MANAGEMENT CO LLC holds $100,867,259 across 3 Specialty Business Services names. AMTM ranks #1 (84.9% of the industry book) .

#	Ticker	Company	Shares	Value (USD)
1	AMTM	Amentum Holdings, Inc. This page	4,143,971	$85,655,880
2	CTAS	Cintas Corp	58,459	$9,942,706
3	DLB	Dolby Laboratories, Inc.	100,203	$5,268,673

6 filing rows on record

Report Date	Value (USD)	Shares	Change	Type	Discretion	Filed
2026-06-30	$85,655,880	4,143,971	-15.9%	Shares	Sole	2026-08-14
2026-03-31	$128,579,876	4,930,210	-14.6%	Shares	Sole	2026-05-15
2025-12-31	$167,416,304	5,772,976	+11.0%	Shares	Sole	2026-02-17
2025-09-30	$124,604,186	5,202,680	-4.7%	Shares	Sole	2025-11-14
2025-06-30	$128,928,142	5,460,743	+52.6%	Shares	Sole	2025-08-14
2025-03-31	$65,132,922	3,578,732	—	Shares	Sole	2025-05-15
No filing history on record for this holder in this stock.