FISN DEEP FISSION, INC.

“we identified errors related to valuations of SAFE Notes and stock-based compensation expense and determined that (i) our previously issued audited consolidated financial statements for the fiscal year ended December 31, 2024 and for the period from July 17, 2023 (inception) through December 31, 2023, and the unaudited condensed consolidated financial statements for the quarters ended June 30, 2024, September 30, 2024, June 30, 2025, and September 30, 2025 should no longer be relied upon”

“Our Chief Executive Officer and Chief Financial Officer also have concluded that our disclosure controls and procedures were not effective as of September 30, 2026 due to material weaknesses in internal control over financial reporting.”

“We recently restated certain previously issued consolidated financial statements to correct certain errors and have identified material weaknesses in our internal control over financial reporting that caused our management to conclude that we did not maintain effective internal control over financial reporting and that our disclosure controls and procedures were not effective as of September 30, 2026.”

“We recently restated certain previously issued consolidated financial statements to correct certain errors and have identified material weaknesses in our internal control over financial reporting that caused our management to conclude that we did not maintain effective internal control over financial reporting and that our disclosure controls and procedures were not effective as of September 30, 2026.”

“We recently restated certain previously issued consolidated financial statements to correct certain errors and have identified material weaknesses in our internal control over financial reporting that caused our management to conclude that we did not maintain effective internal control over financial reporting and that our disclosure controls and procedures were not effective as of September 30, 2026.”

“we have hired key personnel with relevant financial reporting and controls expertise to strengthen our finance and accounting function, and to address the material weaknesses related to IT general controls and segregation of duties”

“our disclosure controls and procedures were not effective as of September 30, 2026 due to the material weaknesses in internal control over financial reporting, as previously disclosed in Part II, Item 9A of our Annual Report and continue to exist as of September 30, 2026.”

“As discussed in Note 2 to the Company s Annual Report on Form 10-K for the year ended December 31, 2025, the Company restated its previously issued consolidated financial statements, including the unaudited condensed consolidated financial statements for the three and nine month periods ended September 30, 2025, to correct errors related to the valuation of certain SAFE Notes and stock-based compensation.”