Goodwill represents the excess of the purchase price over the fair value of net tangible and identifiable intangible assets acquired in a business combination. The carrying value of goodwill as of October 31, 2020 and February 1, 2020 is $5.3 billion. See “Note 3 - Business Combinations” for discussion of the acquisitions and changes to the carrying value of goodwill.

In connection with the Cavium acquisition on July 6, 2018, the Aquantia acquisition on September 19, 2019 and the Avera acquisition on November 5, 2019, the Company recognized $3.3 billion of intangible assets. As of October 31, 2020 and February 1, 2020, net carrying amounts are as follows (in thousands, except for weighted-average remaining amortization period):


	October 31, 2020
	Gross Carrying Amounts		Accumulated Amortization		Net Carrying Amounts		Weighted-Average Remaining Amortization Period (Years)
Developed technologies	$	2,441,000	$	(640,888)	$	1,800,112	5.78
Customer contracts and related relationships	643,000		(203,868)		439,132		5.87
Trade names	23,000		(12,862)		10,138		2.37
Total acquired amortizable intangible assets	$	3,107,000	$	(857,618)	$	2,249,382	5.78
IPR&D	131,000		—		131,000		n/a
Total acquired intangible assets	$	3,238,000	$	(857,618)	$	2,380,382

The Company regularly analyzes the results of its business to determine whether events or circumstances exist that indicate whether the carrying amount of the intangible assets may not be recoverable. During the second quarter ended August 1, 2020, impairment charges of $50.3 million related to certain intangible assets acquired from Cavium were recognized as part of restructuring actions. The gross carrying amounts and the accumulated amortization of those impaired intangible assets were excluded from the table above. See “Note 5 - Restructuring” for additional information.


	February 1, 2020
	Gross Carrying Amounts		Accumulated Amortization		Net Carrying Amounts		Weighted-Average Remaining Amortization Period (Years)
Developed technologies	$	2,511,000	$	(413,735)	$	2,097,265	6.41
Customer contracts and related relationships	643,000		(128,939)		514,061		6.61
Trade names	23,000		(8,726)		14,274		2.96
Total acquired amortizable intangible assets	$	3,177,000	$	(551,400)	$	2,625,600	6.43
IPR&D	139,000		—		139,000		n/a
Total acquired intangible assets	$	3,316,000	$	(551,400)	$	2,764,600

The intangible assets are amortized on a straight-line basis over the estimated useful lives, except for certain Cavium customer contracts and related relationships, which are amortized using an accelerated method of amortization over the expected customer lives, which more closely align with the pattern of realization of economic benefits expected to be obtained. The IPR&D will be accounted for as an indefinite-lived intangible asset and will not be amortized until the underlying projects reach technological feasibility and commercial production at which point the IPR&D will be amortized over the estimated useful life. Useful lives for these IPR&D projects are expected to range between 3 to 10 years. In the event the IPR&D is abandoned, the related assets will be written off.

Amortization expense for acquired intangible assets for the three and nine months ended October 31, 2020 was $109.4 million and $333.9 million, respectively. Amortization expense for acquired intangible assets for the three and nine months ended November 2, 2019 was $92.8 million and $253.5 million, respectively.