Deep Fission, Inc. is an American nuclear-energy company based in Berkeley, California. Founded in 2023 by Elizabeth Muller and her father, physicist Richard A. Muller, the company is developing an underground reactor concept it calls the Gravity Reactor, which it describes as a pressurized water reactor intended for emplacement in a deep borehole approximately one mile (1.6 km) below the surface. In August 2025, the U.S. Department of Energy (DOE) selected Deep Fission for its Reactor Pilot Program, a pathway for testing advanced reactors outside the national laboratories. It is a development-stage company and had not built or licensed a reactor as of 2026. Deep Fission became an SEC-reporting company through a reverse merger in 2025 and completed an initial public offering in June 2026; its shares trade on the Nasdaq under the ticker symbol FISN.
| trading_symbol | registrant_name | time | price | change | percentage_change |
|---|---|---|---|---|---|
| FISN | DEEP FISSION, INC. | 2026-08-31 09:52:01 | 6.68 | 0.09 | 1.37 |
| trading_symbol | central_index_key | registrant_name | isin_number | lei_number | ein_number | exchange | sic_code | sic_description | fiscal_year_end | state_of_incorporation | address_street | address_city | address_state | address_zip_code | address_country | address_country_code | phone_number | mailing_address | business_address | former_name | industry | founding_date | chief_executive_officer | number_of_employees | website | market_cap | shares_issued | shares_outstanding | description | update_time |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FISN | 0001918102 | DEEP FISSION, INC. | US2439271006 | 254900FXBKM1MS64FV40 | 874265302 | Nasdaq | 4911 | Electric Services | 1231 | DE | 2831 GARBER STREET | BERKELEY | CA | 94705 | UNITED STATES | US | (707) 400-0778 | 2831 GARBER STREET, BERKELEY, CA, 94705 | 2831 GARBER STREET, BERKELEY, CA, 94705 | Surfside Acquisition Inc. | Nuclear power | 2023 | Elizabeth Muller | — | https://www.deepfission.com | 0 | 59,745,938 | 58,905,938 | Deep Fission, Inc. is an American nuclear-energy company based in Berkeley, California. Founded in 2023 by Elizabeth Muller and her father, physicist Richard A. Muller, the company is developing an underground reactor concept it calls the Gravity Reactor, which it describes as a pressurized water reactor intended for emplacement in a deep borehole approximately one mile (1.6 km) below the surface. In August 2025, the U.S. Department of Energy (DOE) selected Deep Fission for its Reactor Pilot Program, a pathway for testing advanced reactors outside the national laboratories. It is a development-stage company and had not built or licensed a reactor as of 2026. Deep Fission became an SEC-reporting company through a reverse merger in 2025 and completed an initial public offering in June 2026; its shares trade on the Nasdaq under the ticker symbol FISN. | 2026-08-27 21:02:56 |
| Fiscal Year | Market Cap | Change In Market Cap | Percentage Change In Market Cap | Shares Outstanding | Change In Shares Outstanding | Percentage Change In Shares Outstanding |
|---|---|---|---|---|---|---|
| 2025 | 0 | 0 | 100 | 56,207,422 | 51,207,422 | 1,024.1484 |
| 2024 | 0 | 0 | 100 | 5,000,000 | 0 | 0 |
| 2023 | 0 | 0 | 100 | 5,000,000 | 0 | 0 |
| Executive Name | Executive Position | Fiscal Year | Salary | Bonus | Stock Awards | Incentive Plan Compensation | Other Compensation | Total Compensation |
|---|---|---|---|---|---|---|---|---|
| Elizabeth A. Muller | Chief Executive Officer, President | 2025 | 400,000 | 60,000 | 3,956,047 | — | 34,008 | 7,116,217 |
| Richard A. Muller | Chief Technology Officer | 2025 | 300,000 | 90,000 | 0 | — | 0 | 1,698,466 |
| Michael Brasel | Chief Operating Officer | 2025 | 242,898 | 72,500 | 90,418 | — | 30,322 | 706,128 |
| Malcolm Thompson | Chief Operating Officer | 2025 | 160,417 | 0 | 3,440,304 | — | 62,500 | 3,663,221 |
| Ian Jacobs | Chief Executive Officer | 2025 | 0 | 0 | 0 | — | 0 | 0 |
| Fiscal Year | 2025 | 2024 | 2023 |
|---|---|---|---|
| Revenue | — | — | — |
| Cost Of Revenue | — | — | — |
| Gross Profit | 0 | — | — |
| Research And Development Expenses | 6,617,562 | — | — |
| General And Administrative Expenses | 14,766,607 | 44,810 | 47,625 |
| Operating Expenses | 21,384,169 | — | — |
| Operating Income | -21,384,169 | -44,810 | -47,625 |
| Net Income | -61,002,954 | -44,810 | -47,625 |
| Earnings Per Share Basic | -2.41 | -0.01 | -0.01 |
| Earnings Per Share Diluted | — | -0.01 | -0.01 |
| Weighted Average Shares Outstanding Basic | 25,332,277 | 5,000,000 | 5,000,000 |
| Weighted Average Shares Outstanding Diluted | — | 5,000,000 | 5,000,000 |
| Fiscal Year | 2025 | 2024 | 2023 |
|---|---|---|---|
| Cash And Cash Equivalents | 23,719,422 | 3,464 | 774 |
| Marketable Securities Current | — | — | — |
| Accounts Receivable | — | — | — |
| Inventories | — | — | — |
| Non Trade Receivables | — | — | — |
| Other Assets Current | 713,154 | — | — |
| Total Assets Current | 24,432,576 | 3,464 | 774 |
| Marketable Securities Non Current | — | — | — |
| Property Plant And Equipment | 37,102 | — | — |
| Other Assets Non Current | — | — | — |
| Total Assets Non Current | 258,509 | 0 | 0 |
| Total Assets | 24,691,085 | 3,464 | 774 |
| Accounts Payable | 538,270 | 10,700 | 10,700 |
| Deferred Revenue | — | — | — |
| Short Term Debt | — | — | — |
| Other Liabilities Current | 185,164 | — | — |
| Total Liabilities Current | 2,403,972 | 157,725 | 110,225 |
| Long Term Debt | — | — | — |
| Other Liabilities Non Current | — | — | — |
| Total Liabilities Non Current | 0 | 0 | 0 |
| Total Liabilities | 2,403,972 | 157,725 | 110,225 |
| Common Stock | 5,110 | 500 | 500 |
| Retained Earnings | -66,727,099 | -154,761 | -109,951 |
| Accumulated Other Comprehensive Income | — | — | — |
| Total Shareholders Equity | 22,287,113 | -154,261 | -109,451 |
| Fiscal Year | 2025 | 2024 | 2023 |
|---|---|---|---|
| Depreciation And Amortization | 8,327 | — | — |
| Share Based Compensation Expense | 8,424,803 | — | — |
| Other Non Cash Income Expense | — | — | — |
| Change In Accounts Receivable | — | — | — |
| Change In Inventories | — | — | — |
| Change In Non Trade Receivables | — | — | — |
| Change In Other Assets | — | — | — |
| Change In Accounts Payable | 443,473 | — | 1,348 |
| Change In Other Liabilities | 153,387 | — | — |
| Cash From Operating Activities | -13,051,195 | -44,810 | -46,277 |
| Purchases Of Marketable Securities | — | — | — |
| Sales Of Marketable Securities | — | — | — |
| Acquisition Of Property Plant And Equipment | 43,436 | — | — |
| Acquisition Of Business | — | — | — |
| Other Investing Activities | — | — | — |
| Cash From Investing Activities | -43,436 | — | — |
| Tax Withholding For Share Based Compensation | — | — | — |
| Payments Of Dividends | — | — | — |
| Issuance Of Common Stock | 30,000,000 | — | — |
| Repurchase Of Common Stock | — | — | — |
| Issuance Of Long Term Debt | — | — | — |
| Repayment Of Long Term Debt | — | — | — |
| Other Financing Activities | — | — | — |
| Cash From Financing Activities | 30,085,158 | 47,500 | 46,982 |
| Change In Cash | 16,990,527 | — | — |
| Cash At End Of Period | 23,719,422 | 3,464 | 774 |
| Income Taxes Paid | — | — | — |
| Interest Paid | — | — | — |
| Fiscal Year | 2025 | 2024 | 2023 |
|---|---|---|---|
| Earnings Per Share | -2.41 | -0.01 | -0.01 |
| Price To Earnings Ratio | -6.0415 | -1,456 | -1,456 |
| Earnings Growth Rate | 24,000 | 0 | 0 |
| Price Earnings To Growth Ratio | -0.0003 | — | — |
| Book Value Per Share | 0.8798 | -0.0309 | -0.0219 |
| Price To Book Ratio | 16.5494 | -471.9274 | -665.1378 |
| Ebitda | -60,994,627 | — | — |
| Enterprise Value | — | — | — |
| Dividend Yield | — | — | — |
| Dividend Payout Ratio | — | — | — |
| Debt To Equity Ratio | — | — | — |
| Capital Expenditures | — | — | — |
| Free Cash Flow | — | — | — |
| Return On Equity | -2.7371 | 0.2905 | 0.4351 |
| One Year Beta | — | — | — |
| Three Year Beta | — | — | — |
| Five Year Beta | — | — | — |
| Insider Name | Relationship To Issuer | Transaction Date | Amount Of Securities | Acquired Or Disposed | Securities Owned Following Transaction |
|---|---|---|---|---|---|
| Angell Jonathon | Director | 2026-07-23 | 16,973 | A | 16,973 |
| Goldman Tepper Leslie | Director | 2026-07-23 | 19,204 | A | 19,204 |
| JANOVER BLAKE | Director | 2026-07-23 | 18,962 | A | 18,962 |
| GLANVILLE THOMAS S | Director | 2026-07-23 | 19,156 | A | 19,156 |
| Investor Name | Period Of Report | Market Value | Amount Of Securities | Price Per Security |
|---|---|---|---|---|
| GOLDMAN SACHS GROUP INC | 2026-06-30 | 191,798 | 17,373 | 11.04 |
| CITADEL ADVISORS LLC | 2026-06-30 | 1,214,400 | 110,000 | 11.04 |
| WELLS FARGO & COMPANY/MN | 2026-06-30 | 3,698 | 335 | 11.0388 |
| JONES FINANCIAL COMPANIES LLLP | 2026-06-30 | 3,225 | 300 | 10.75 |
| PRELUDE CAPITAL MANAGEMENT, LLC | 2026-06-30 | 162,443 | 14,714 | 11.04 |