Identifiable intangible assets consist of acquired customer contracts and relationships, trademarks and non-compete agreements. Amortization expense related to intangible assets was $35.8, $44.5 and $51.5 for the years ended September 30, 2024, September 30, 2023 and September 30, 2022, respectively. These assets are amortized over their estimated useful lives, the reasonableness of which are continually evaluated by the Company. There were no intangible assets acquired during the year ended September 30, 2024. The weighted average amortization period of intangible assets acquired during the year ended September 30, 2023 was seven years.

Intangible assets as of September 30, 2024 and September 30, 2023 consisted of the following:


		September 30, 2024					September 30, 2023
	Estimated Useful Life	Gross Carrying Amount		Accumulated Amortization			Gross Carrying Amount		Accumulated Amortization
Customer relationships	6-21 yrs.	$	715.9	$	(620.1	)	$	725.5	$	(594.1	)
Trademarks	12 yrs.		—		—			3.8		(2.9	)
Non-compete agreements	5 yrs.		—		—			2.7		(2.7	)
Total intangible assets		$	715.9	$	(620.1	)	$	732.0	$	(599.7	)

Amortization expense is anticipated to be as follows in future years:


Fiscal Year Ended September 30,
2025	$	29.3
2026		21.8
2027		15.2
2028		11.1
2029		7.2
2030 and thereafter		11.2
	$	95.8

The following is a summary of the goodwill activity for the periods ended September 30, 2023 and September 30, 2024:


	Maintenance Services			Development Services		Total
Balance, September 30, 2022	$	1,792.7		$	216.1	$	2,008.8
Acquisitions (1)		10.7			1.9		12.6
Balance, September 30, 2023	$	1,803.4		$	218.0	$	2,021.4
Acquisitions (1)		0.1			—		0.1
Divestiture		(5.8	)		—		(5.8	)
Balance, September 30, 2024	$	1,797.7		$	218.0	$	2,015.7

(1)

The acquisitions adjustments include the immaterial impact of foreign currency and other prior year measurement period adjustments during the respective periods.

The Company performed its annual goodwill impairment assessment as of July 1, 2024 utilizing a quantitative test approach as described in Note 2 "Summary of Significant Accounting Policies".

During the year ended September 30, 2023, the Company acquired, through a series of separate transactions, 100% of the operations of three unrelated companies, all of which was allocated to Maintenance Services. The Company paid approximately $13.8 in aggregate consideration for the acquisitions, net of cash acquired. The Company accounted for the business combinations under the acquisition method and, accordingly, recorded the assets acquired and liabilities assumed at their estimated fair market values based on management’s preliminary estimates, with the excess allocated to goodwill. The purchase accounting related to these acquisitions was finalized within one year from each acquisition date. As a result of final purchase accounting, certain of the fair value amounts previously estimated were adjusted during the measurement period. The fair values were primarily estimated using Level 3 assumptions within the fair value hierarchy, including estimated future cash flows, discount rates and other factors. The measurement period adjustments were not material to the Consolidated Balance Sheets as of September 30, 2024 and September 30, 2023. The identifiable assets acquired as part of the fiscal 2023 acquisitions were primarily customer relationship intangible assets of $4.0. The amount allocated to goodwill is reflective of the benefits the Company expects to realize from anticipated synergies and the acquired assembled workforce in place. A portion of the goodwill resulting from the acquisitions is deductible for tax purposes.

From each acquisition date through September 30, 2023, the amount of revenue of the companies acquired during fiscal 2023 included in our Consolidated Statement of Operations for the year ended September 30, 2023, was $16.0.

On January 12, 2024, the Company completed the sale of one of its fully owned subsidiaries, U.S. Lawns, for total cash consideration of $51.0. The gain on the transaction of $43.6 is included in Gain on divestiture in the Consolidated Statements of Operations for the year ended September 30, 2024. The Maintenance Services operating segment includes the operations of the divested entity, and its results of operations are included in the Consolidated Statements of Operations through January 12, 2024. The company disposed of the U.S. Lawns customer relationships and trademarks as part of the divestiture.