Quarterly report pursuant to Section 13 or 15(d)

Intangible Assets, Net

Intangible Assets, Net
3 Months Ended
Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]  
Intangible Assets, Net Intangible Assets, Net 
Intangible assets, net consisted of the following:
  March 31, 2021 December 31, 2020
  Gross   Net Gross   Net
  Carrying Accumulated Carrying Carrying Accumulated Carrying
  Amount Amortization Amount Amount Amortization Amount
(in thousands)
Customer lists $ 591,520  $ (210,466) $ 381,054  $ 591,520  $ (198,555) $ 392,965 
Proprietary technologies 78,424  (29,334) 49,090  54,914  (26,949) 27,965 
Trade names 33,700  (20,821) 12,879  33,700  (19,589) 14,111 
Total intangible assets $ 703,644  $ (260,621) $ 443,023  $ 680,134  $ (245,093) $ 435,041 

There were no material retirements of intangible assets during the three months ended March 31, 2021 and 2020.

Amortization expense was as follows:
  Three Months Ended
  March 31,
  2021 2020
(in thousands)
Amortization expense $ 16,478  $ 18,758 

Acquisition of Proprietary Technology

The Company previously owned approximately 29% of the outstanding units in a privately held company and accounted for it as an equity method investment. On March 11, 2021, the Company entered into an intellectual property purchase agreement with this privately held company to acquire all of the proprietary technology developed by the privately held company for approximately $35.5 million. Concurrent with the intellectual property purchase agreement, the Company also entered into a redemption agreement with the same privately held company to redeem its previously held equity interest for approximately $10.0 million. The Company accounted for these two arrangements as a single unit of account. As of the acquisition date, the net cost of the proprietary technology acquired, including capitalized transaction costs, was approximately $24.5 million, which will be amortized over a five-year period on a straight-line basis. The proprietary technology has been integrated into the Envestnet Wealth Solutions segment.