Deep Fission (FISN): which funds own it

Who owns Deep Fission?

Holders reporting more than 5% of the shares to the SEC (Schedules 13D/13G): Muller Elizabeth, 20.6% (13D filed Sep 23, 2025), Muller Richard, 10.6% (13D filed Sep 23, 2025), Mark N.Tompkins, 5.6% (13G/A filed May 15, 2026) and EE Holdings, 5.5% (13G filed Nov 3, 2025). As of Jun 30, 2026, the largest holders reported on Form 13F were Blue Owl Capital Holdings (2.4% of the shares), Elevation Wealth Management (0.5%) and UBS Group (0.4%).

Sources:13D by Muller Elizabeth (Sep 23, 2025) ↗13D by Muller Richard (Sep 23, 2025) ↗13G/A by Mark N.Tompkins (May 15, 2026) ↗13G by EE Holdings (Nov 3, 2025) ↗All of the company's proxy statements on EDGAR ↗

13F percentages divide the shares each institution reports by the shares outstanding on the cover of the company's latest report before the quarter end (May 4, 2026). Entities of the same group file separately and are not added up. We hold 13D and 13G filings made since Dec 23, 2024: a holder above 5% that has not filed since then does not appear here.

• Blue Owl Capital Holdings1.3 MPrivate equity or venture capital · 2.26% of the company+1.3 M
• Elevation Wealth Management298 KWealth adviser · 0.51% of the company+298 K
• UBS Group198 KBank or trading desk · 0.34% of the company+198 K
• Consolidated Press International Holdings133 KPrivate equity or venture capital · 0.23% of the company+133 K
• Citadel Advisors110 KQuant or multi-manager · 0.19% of the company+110 K
• LPL Financial71 KWealth adviser · 0.12% of the company+71 K
• Geode Capital Management27 KIndex manager · 0.05% of the company+27 K
• Essential Investment Partners26 KType not verified · 0.04% of the company+26 K
• Chapin Davis19 KType not verified · 0.03% of the company+19 K
• Goldman Sachs Group17 KBank or trading desk · 0.03% of the company+17 K

The 10 13F filers with the most shares as of Jun 30, 2026, whatever their type (index firms usually come first). “Change”: shares added or cut versus the previous quarter, split-adjusted; “no data” = there is no comparable portfolio for the previous quarter (no filing, or a filing with its holdings under confidential treatment). “% of the company” only where shares outstanding are up to date. Entities of the same group file separately and some 13F filings include other managers: there may be double counting. With a free account: the top 25, the largest buyers and the largest sellers.

Held by institutions (13F)

Institutions (13F): 4.1% of the shares · top 10: 4.0% · in index firms: 1.2% of the institutional total

Shares reported by the 21 13F filers as of Jun 30, 2026, divided by the shares outstanding on the cover of the company's latest report (May 4, 2026). It is not all institutional ownership: only managers above $100M file a 13F, and it excludes short positions. Entities of the same group file separately and some 13F filings include other managers: there may be double counting. We only publish it where the figure is credible: not for ADRs, companies with more than one share class or stale shares-outstanding data.

Shares outstanding: buybacks and dilution

From the statements the company filed with the SEC (10-K). The change compares average diluted shares of each fiscal year, on today's basis: negative = it bought back more than it issued; positive = dilution. “No data” = the company does not report that item under a tag we can read; it does not mean zero.

Earnings quality and debt

From the figures the company filed with the SEC. Cash flow over net income near or above 1 means earnings are collected in cash; far below, that part is accounting. Coverage says how many times operating income pays the latest fiscal year's interest. Maturities come from the debt note of the latest annual report, counted from its closing date. “No data” never means zero.

Above 5% over time (13D/13G)

Each holder with its filings in order. History since December 2024.

Flagged material events (8-K)

• Apr 9, 2026Seriousfiling ↗

  Previously issued financial statements can no longer be relied on (Item 4.02)

• Mar 5, 2026Mediumfiling ↗

  Change of auditor (Item 4.01)

• Jul 17, 2026Routinefiling ↗

  Change in directors or officers (Item 5.02)

• Feb 25, 2026Routinefiling ↗

  Change in directors or officers (Item 5.02)

• Feb 10, 2026Routinefiling ↗

  Unregistered sale of equity securities (Item 3.02)

• Dec 22, 2025Routinefiling ↗

  Change in directors or officers (Item 5.02)

• Dec 11, 2025Routinefiling ↗

  Change in directors or officers (Item 5.02)

• Nov 12, 2025Routinefiling ↗

  Change in directors or officers (Item 5.02)

Alert items the company itself flagged in its 8-K filings with the SEC, most serious first. It is the form's label, with no interpretation from us: Item 5.02 covers routine appointments as well as a chief executive's departure; open the filing. The quoted headline is the original press release's.