Volume IV · Issue 02 · Proprietary Tools
The cap table
we built for the
financings we close.
WhimiStack is the equity-modeling instrument our partners use on every priced round, SAFE, convertible note, and 409A we touch. It started as an internal spreadsheet. It is now used by 1,800+ CFOs and cap-table admins across the portfolio we serve.
Request WhimiStack Access
Editor's Note · No. 01
Why we built our own.
The honest version is that we got tired of paying for tools that didn't model the way deals actually close.
After closing 412 financings between 2021 and 2024 — SAFEs, convertible notes, priced rounds, secondary tenders — we kept running into the same modeling gaps. Standard cap-table platforms treat dilution as a math problem. It is not. It is a sequence problem: what happens to the option pool top-up when the SAFE converts, then what happens to the note when the priced round triggers, then what happens to the founder's common when the 409A refreshes mid-process. Most tools let you set one scenario at a time. We needed to stack them.
WhimiStack is the result. It is not a consumer product; it is a working instrument we use ourselves on every matter, and we open it to a narrow circle of CFOs, cap-table admins, and family-office principals who need the same modeling depth we do. It is our internal know-how, given a user interface.
We are not in the business of unseating Carta or Pulley. We built WhimiStack because our financings demanded a tool that understood the legal sequence of a deal, not just the spreadsheet arithmetic. If that is the kind of fidelity you need in your cap table, it will probably fit your hand.
Chapter II · The Modules
What is actually inside.
Four working modules, each one modeled on a deal pattern we see often enough to deserve a permanent place in the tool. No roadmap vapor. No "coming soon."
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I.
Cap-Table Modeling
A live, multi-tier cap table that holds common, options, warrants, SAFEs, convertible notes, and preferred — with a clean audit trail for every grant, conversion, and re-pricing. Built to handle the kind of messy, pre-Series-A stacks founders actually live inside.
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II.
Scenario Engine
Stack an unlimited number of what-ifs — pool top-ups, secondaries, tender offers, structured exits — and compare them side by side. Founder-friendly defaults show per-share, per-founder, and per-employee dilution rather than just option-pool totals.
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III.
SAFE & Note Conversion
Model Y Combinator SAFEs (post-money and pre-money), convertible notes with caps and discounts, and MFN clauses — then watch the conversion rules play out across a priced round automatically. Honors side-letter carve-outs and pro-rata rights.
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IV.
409A-Aware Valuation
Connect a 409A report and the model reconciles fair-market value, strike-price floors, and the resulting incremental ISO disqualification exposure. Tracks the dilution waterfall from common through preferred through exit, with sensitivity bands around the FMV.
Chapter III · Used in the Wild
Numbers, not narrative.
CFOs and cap-table admins running the tool across the portfolio.
Modeling runs completed in Q1 2025 alone.
Financings modeled pre-close between 2021 and 2024.
Average scenarios modeled per round, before term sheet.
Drawn from the WhimiStack access log, partner-validated and anonymized. Updated quarterly.
Chapter IV · In the Words of Operators
What it is like to use it.
Series C · Fintech · Used through three rounds
“WhimiStack caught a 4.1% founder dilution gap that two prior tools had missed — the SAFE conversion was double-counting the option-pool top-up. It saved a six-hour argument with our lead investor's counsel.”
Series B · Climate Tech · Cap-table admin
“I run 11 companies on WhimiStack. The scenario engine is the only one I've seen that lets me stack a tender offer on top of a priced round on top of a refresh without breaking the model. The exits module alone is worth the access.”
Family Office · Two-portfolio oversight
“We needed a tool that spoke the language of a legal sequence, not a spreadsheet. The partners review our access every quarter, which I actually prefer — it keeps the circle small and the answers sharp.”
Chapter V · Access
Request WhimiStack access.
Access is partner-reviewed and granted within two business days. We are not a self-serve platform — the user list is small on purpose, and every request is read by a partner before credentials are issued.
- Best fit for CFOs, cap-table admins, and GC-vetted founders at Series A–C companies.
- Family-office principals reviewing portfolio cap tables are welcome.
- Expect a short video walk-through and a 30-minute orientation call before credentials are issued.