Intangible Assets

The Company recorded $3.2 million, $1.0 million, and $1.7 million of customer base intangible assets during the six months ended March 31, 2020 related to the acquisitions of UOB Bullion and Futures Limited, IFCM Commodities GmbH, and Quest Capital, respectively, as further discussed in Note 18.

The gross and net carrying values of intangible assets as of the balance sheet dates, by major intangible asset class are as follows (in millions):



	March 31, 2020							September 30, 2019
	Gross Amount		Accumulated Amortization			Net Amount		Gross Amount		Accumulated Amortization			Net Amount
Intangible assets subject to amortization:
Software programs/platforms	$	5.3	$	(3.2	)	$	2.1	$	5.3	$	(3.0	)	$	2.3
Customer base	28.2		(14.2		)	14.0		22.1		(12.5		)	9.6
Total intangible assets subject to amortization:	33.5		(17.4		)	16.1		27.4		(15.5		)	11.9

Intangible assets not subject to amortization:
Website domains	2.1		—			2.1		2.1		—			2.1
Business licenses	2.7		—			2.7		2.7		—			2.7
Total intangible assets not subject to amortization:	4.8		—			4.8		4.8		—			4.8
Total intangible assets	$	38.3	$	(17.4	)	$	20.9	$	32.2	$	(15.5	)	$	16.7

Amortization expense related to intangible assets was $1.1 million and $0.6 million for the three months ended March 31, 2020 and 2019, respectively. Amortization expense related to intangible assets was $1.9 million and $1.3 million for the six months ended March 31, 2020 and 2019, respectively.

As of March 31, 2020, the estimated future amortization expense was as follows:



(in millions)
Fiscal 2020 (remaining six months)	$	2.0
Fiscal 2021	4.0
Fiscal 2022	2.7
Fiscal 2023	2.5
Fiscal 2024 and thereafter	4.9
Total intangible assets subject to amortization	$	16.1