| Merger and Restructuring Costs |
The following table summarizes merger, acquisition, and restructuring cost activity (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended | | Nine Months Ended | | | | September 30, 2021 | | September 30, 2022 | | September 30, 2021 | | | (in thousands) | | Professional services (investment banking advisory, legal and other professional services) | | | $ | 1,064 | | | $ | 917 | | | $ | 28,032 | | | Personnel related (severance and one-time termination benefit costs) | | | 1,312 | | | 1,227 | | | 6,176 | | | Non-cash stock-based compensation (double-trigger acceleration and severance) | | | 48 | | | 2,004 | | | 1,070 | | Impairment costs of abandoned technology | | | — | | | 3,320 | | | — | | | Loss contracts (lease related) | | | — | | | — | | | 2,500 | | | Total merger, acquisition, and restructuring costs | | | $ | 2,424 | | | $ | 7,468 | | | $ | 37,778 | |
| | | | | | | (in thousands) | Accrued restructuring costs at December 31, 2021 | $ | 2,742 | | | Restructuring costs, personnel related and non-cash stock-based compensation | 3,231 | | | Restructuring costs, impairments | 3,320 | | | | | Cash paid for restructuring costs | (2,571) | | | | | Non-cash impairments | (3,320) | | | Non-cash stock-based compensation | (2,004) | | Accrued restructuring costs at September 30, 2022 | $ | 1,398 | |
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