v3.22.0.1
Intangible Assets and Goodwill
 12 Months Ended
Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]  
Intangible Assets and Goodwill Intangible Assets and Goodwill
Intangible Assets

Identifiable intangible assets consisted of the following (in thousands):

December 31, 2020December 31, 2021
Gross
Carrying
Amount (1)		Accumulated
Amortization (1)		Net
Carrying
Value		Gross
Carrying
Amount (1)		Accumulated
Amortization (1)		Net
Carrying
Value
Listing relationships$42,501 $(9,492)$33,009 $42,501 $(15,467)$27,034 
Customer contacts4,346 (2,159)2,187 4,346 (3,570)776 
Developed technology37,800 (28,417)9,383 22,900 (20,956)1,944 
Trade names35,753 (13,823)21,930 33,163 (17,980)15,183 
Other9,652 (275)9,377 9,650 (2,279)7,371 
Total intangible assets$130,052 $(54,166)$75,886 $112,560 $(60,252)$52,308 
(1) Excludes write off of intangible assets that have been fully amortized.

Amortization expense related to intangible assets for the years ended December 31, 2019, 2020, and 2021 was $46.1 million, $36.2 million, and $23.6 million, respectively.
Estimated future amortization expense for intangible assets as of December 31, 2021 was as follows (in thousands):

Year Ending December 31,Amount
2022$16,320 
202312,065 
20246,988 
20255,313 
20263,679 
Thereafter7,943 
Total future amortization expense$52,308 

Goodwill

The changes in the carrying amount of goodwill for the years ended December 31, 2020 and 2021 were as follows (in thousands):

Amount
Balance as of December 31, 2019$652,088 
Foreign currency translation adjustments3,713 
Balance as of December 31, 2020655,801 
Foreign currency translation adjustments(3,199)
Balance as of December 31, 2021$652,602