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Home › Insider trades › Deep Fission › Director sold ~$3 of FISN shares in the open market
Approx. value · 25K sh @ $0.0001
Holds after · shares reported
Why it stands out A Deep Fission director sold $3 of Deep Fission shares. The filing does not indicate a pre-arranged trading plan.
Written from the filing's own figures. OQRO describes what was reported and never tells you what to buy or sell.
All the details
Dates, kept separate
Transaction date Aug 26, 2025
Reporting period Not applicable
Filed with the SEC Aug 28, 2025 Director <$25K
Context Classification open market sale
Code S — open-market or private sale
Absolute commitment ~$3
Shares × reported transaction price
Planned / mechanical clue None found in footnotes
Only flagged when a footnote says so; never inferred
Record ID
0001213900-25-081957
Filed / recorded Aug 28, 2025, 11:01 PM UTC
Added to OQRO Oct 9, 2026, 10:23 PM UTC
Data quality Verified: identifiers matched exactly
Issuer Surfside Acquisition Inc.
Reporting person Mark N. Tompkins
Relationship Director, 10% owner
Table Non-derivative (Table I)
Transaction date Aug 26, 2025
Acquired / disposed Disposed (D)
Shares owned after 4,725,000
Around the same time Insider buying
10 days before an 8-K Traded Aug 26, 2025 · filed 2 days later
The CEO of Deep Fission paid $3 out of pocket for Deep Fission shares. Shares held went up 10% with this purchase.
The story around this disclosure Every dated public record OQRO holds about the company from 60 days before to 120 days after, oldest first. It shows what was going on; none of it is a stated reason for the trade.
Aug 26, 2025 · this disclosure Insider What came next Aug 26, 2025 Insider · 10 days before an 8-K CEO purchased ~$3 of FISN shares in the open market Sep 5, 2025 Company filing · Form 8-K · Material agreement, Acquisition or sale Completed buying or selling a business or assets, and changed its auditor (and 7 more items) “Departure of Directors or Principal Officers; Election of Directors; Appointment of Principal Officers; Compensatory Arrangements of Certain Officers.” Nov 7, 2025 Company filing · Form 8-K · Executive change Changed a top executive or board member “On November 7, 2025, Richard A. Muller resigned from the Board of Directors of Deep Fission to focus on his continuing responsibilities as the Company’s Chief Technology Officer.” Nov 17, 2025 Company filing · Form 8-K · Material agreement Signed an important agreement Dec 9, 2025 Company filing · Form 8-K · Executive change Changed a top executive or board member “On December 9, 2025, Deep Fission, Inc. entered into an offer letter with Elizabeth Muller, the Company’s President and Chief Executive Officer and Chair of the Board.” Dec 19, 2025 Company filing · Form 8-K · Executive change, Other news Changed a top executive or board member, and reported other company news “On December 19, 2025, the Board of Directors (the “ Board ”) of Deep Fission, Inc. (the “ Company ”) increased the size of the Board to five members and appointed Blake E. Janover and Thomas S. Glanville to the Board, effective immediately.” 