Momentus Results Presentation Deck

CY 2023 GAAP to Non- GAAP Reconciliations View from Vigoride-5 A reconciliation of selling, general, and administrative expenses to non-GAAP selling, general, and administrative expenses for the three months ended March 31, 2023, March 31, 2022, and December 31, 2022, is set forth below: (in thousands) Selling, general, and administrative expenses Stock-based compensation SEC and CFIUS legal expenses Class action litigation legal expenses Other non-recurring litigation legal expense SEC compliance costs NSA compliance costs Severance and other non-recurring expenses¹ Non-GAAP selling, general, administration expenses March 31, 2023 S $ Three Months Ended March 31, 2022 December 31, 2022 10,270 $ 1,244 $ 85 110 $ 1,219 22 232 7,358 $ March 31, 2023 14,853 $ 1,839 795 795 114 2,135 978 1 - Loss contingencies for certain severance agreements were reversed when the Company determined they would not be signed and paid A reconciliation of research and development expenses to non-GAAP research and development expenses for the three months ended March 31, 2023, March 31, 2022, and December 31, 2022, is set forth below: 8,197 $ Three Months Ended March 31, 2022 10,119 $ 514 476 122 9,007 $ (in thousands) Research and development expenses Prepaid launch deposit impairment Stock-based compensation Severance and non-recurring expenses Non-GAAP Research and development expenses 1 - Loss contingencies for certain severance agreements were reversed when the Company determined they would not be signed and paid 10,929 2,534 161 755 1,004 76 233 9,971 $ 6,166 373 350 9,248 $ December 31, 2022 10,283 510 9,773 21

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