| Schedule of intangible assets |
The gross carrying amount and accumulated amortization of the Company’s acquired identifiable intangible assets as of September 30, 2026 were as follows (in thousands): | | | | | | | | | | | | | | Weighted Average | | Gross Carrying | | Accumulated | | | | | | Amortization Period | | Amount | | Amortization | | Total | Acquired technology | | 11 years | | $ | 15,992 | | $ | (4,224) | | $ | 11,768 | Dry stack electrolyzer technology | | 10 years | | | 11,351 | | | (3,061) | | | 8,290 | Customer relationships, trade name, and other | | 14 years | | | 7,319 | | | (1,018) | | | 6,301 | | | | | $ | 34,662 | | $ | (8,303) | | $ | 26,359 |
The gross carrying amount and accumulated amortization of the Company’s acquired identifiable intangible assets as of December 31, 2025 were as follows (in thousands): | | | | | | | | | | | | | | Weighted Average | | Gross Carrying | | Accumulated | | | | | | Amortization Period | | Amount | | Amortization | | Total | Acquired technology | | 11 years | | $ | 15,997 | | $ | (3,047) | | $ | 12,950 | Dry stack electrolyzer technology | | 10 years | | | 11,352 | | | (1,913) | | | 9,439 | Customer relationships, trade name, and other | | 14 years | | | 7,446 | | | (607) | | | 6,839 | | | | | $ | 34,795 | | $ | (5,567) | | $ | 29,228 |
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| Schedule of amortization expense |
The estimated amortization expense for subsequent years as of September 30, 2026 is as follows (in thousands): | | | Remainder of 2026 | $ | 916 | 2027 | | 3,665 | 2028 | | 3,328 | 2029 | | 3,213 | 2030 | | 3,194 | 2031 and thereafter | | 12,043 | Total | $ | 26,359 |
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