On Founder Liquidity Windows

TL;DR

• The exit number is not the wealth number. Two founders can sell identical companies for identical prices and end up millions apart in what they keep. The difference isn't negotiation or luck — it's how many of the liquidity windows they recognized and acted on before each one closed.
• There are at least four windows, and they close at different times. Structuring (closes before a sale becomes a practical certainty), selling-mechanics (governed by insider-trading timing rules), diversification (closes as a concentrated position drifts), and tax-year (closes December 31). A founder can win one and lose three.
• The most valuable window closes earliest — and earlier than founders think. Multiplying the QSBS exclusion across trusts and family members must be done before a sale becomes a "practical certainty," not merely before closing. The rules changed in July 2025 — the per-issuer cap rose from $10M to $15M — so most founders' knowledge is already stale.
• The selling-mechanics window has a 90-day fuse most founders trigger too late. A 10b5-1 plan carries a mandatory cooling-off period of up to 90 days for directors and officers, capped at 120 days. Changing the plan's core economics resets the clock.
• The cruel pattern: the people most exposed are first-time liquid founders. They built one company, are selling it once, and have never had a reason to learn any of this. The first-timer learns each window exists from the bill that arrives after it closed.

Founders fixate on the headline — the acquisition price, the IPO valuation, the share count times the strike. It's the number that goes in the announcement and the group chat. It is also, in terms of what the founder actually keeps, one of the least decisive numbers in the whole event.

What decides the kept wealth is a series of decisions made around the transaction, each on its own clock, most invisible until missed. Think of it less as a single event and more as a sequence of doors, each open for a while, each closing at a different moment, each worth real money to walk through in time. Miss the door and there is no reopening it — these deadlines are set by tax code, securities law, and the calendar, not by the counterparty.

The founders who keep the most are not the ones who sold highest. They're the ones who recognized each door while it was open. That recognition — not the price — is the variable.

Window 1 — Structuring (closes before a sale is a practical certainty)

This is the earliest and the most valuable. Section 1202 (QSBS) lets an eligible founder exclude the greater of $15M or 10× basis in capital gains from federal tax, per issuer. The cap is per-taxpayer, per-issuer — so gifting shares into separate non-grantor trusts for a spouse and children, well before any sale is on the horizon, gives each its own exclusion. A family of five, structured early, could exclude on the order of $75M from a single company.

The deadline is real, and it's earlier than founders assume. Transfers must be completed before a sale becomes a "practical certainty" — not merely before closing. Gift too close to a deal and the IRS can disregard the structure under the assignment-of-income or step-transaction doctrines; a 2023 Tax Court case (Hoensheid) found a gift made after a binding obligation to sell had arisen left the gain taxable to the donor.

Window 2 — Selling mechanics (governed by a 90-day fuse)

Once liquid, an insider can't just sell. The standard compliant tool, a Rule 10b5-1 plan, carries a mandatory cooling-off period — up to 90 days for directors and officers, capped at 120 days — between adopting the plan and the first permitted trade. The rule exists to separate the decision to sell from any inside information.

The trap inside the trap: modifying the plan's core economics — amount, price, or timing — is treated as terminating it and starting a new one, re-triggering the waiting period. A founder who sets up a plan late, or keeps tinkering with it, can push their actual liquidity out by a full quarter or more.

Window 3 — Diversification (closes as the position drifts)

A founder post-liquidity often holds a hugely concentrated position — most of their net worth in one stock. It "closes" not on a date but on price movement: every month the concentrated position is held, the founder is making an enormous, usually unintended, bet. Founders routinely tell themselves they'll diversify "after it goes up a bit more," which is the concentrated-position version of market timing, and it's how paper fortunes evaporate.

Window 4 — Tax year (closes December 31)

Which calendar year a gain lands in, and how it's paired with offsetting losses or charitable moves, can change the bill materially — and the deadline is the year-end, full stop. This is the window most founders assume their accountant "handles," not realizing the decisions had to be made before the year closed, not at filing time.

There's a pattern in who plays these windows well, and it's almost perfectly inverted from intuition.

The founders who capture every window are the ones who least needed help: serial entrepreneurs who've exited before and learned the doors exist, founders whose sophisticated early investors pushed them toward C-corp structure and early planning, anyone with an advisor in the room years before the event.

The founders who lose windows are the first-timers — the person who built one company over eight years, never had assets to plan around, and is now facing liquidity for the first time. No advisor, because they never needed one. And, by virtue of a concentrated stake in one successful company, the most to lose.

Two consequences follow:

1. The knowledge gap and the wealth sit in the same person. This isn't a market where the sophisticated lose a little. It's one where the unadvised lose the most, across multiple windows, each loss silent and irreversible.
2. The ground keeps moving. QSBS was rewritten in July 2025; 10b5-1 cooling-off rules were tightened in the 2022 amendments that took full effect across 2023-2024. A founder relying on what they absorbed a few years ago is planning against rules that have since changed.

The decisive question is not "do I have a good accountant for tax season." It's "is someone watching all four windows, and did they start early enough to act on the ones that close first."

Illustrative model, not advice. Figures simplified to show the magnitude of timing, and assume stock issued after July 2025; earlier stock keeps the prior $10M cap.

Setup: A founder's share of an exit is $40M, against near-zero basis, stock qualifies as QSBS. Same founder, same price, two versions of the surrounding decisions.

Played reactively (acts only as each event arrives):

• Structuring window: missed. One personal exclusion, ~$15M. Federal tax on the remaining ~$25M at ~23.8% ≈ $5.95M.
• Selling window: 10b5-1 plan set up late; first sale delayed ~90 days.
• Diversification window: holds the concentrated position "until it recovers."
• Tax-year window: gain lands in a high-income year with nothing offsetting it.

Played deliberately (someone watching the windows, starting early):

• Structuring: trusts funded two years prior; multiple exclusions cover most of the gain. Federal tax near zero.
• Selling: 10b5-1 plan adopted well ahead; sales execute on the intended schedule.
• Diversification: position reduced methodically on a pre-set plan.
• Tax-year: gain and charitable/offsetting moves timed across the calendar.

Same $40M. The structuring window alone separates the two by roughly $6M, before the other three windows compound the gap. And the most expensive of the four had likely closed before the reactive founder even saw a term sheet.

QSBS / Section 1202. Greenberg Traurig LLP — "Qualified Small Business Stock (QSBS) Regime Expanded Under One Big Beautiful Bill Act" (July 2025). Foley & Lardner LLP — "QSBS Stacking: Leveraging Gifts and Trusts for Additional Section 1202 Exclusions" (2026). Frost Brown Todd — "Transfer Planning With Qualified Small Business Stock" (Dec 2025). Boland Law Group — "Tax Planning Under IRC § 1202 With Trusts and 'Stacking' Strategies" (July 2025), citing Estate of Hoensheid v. Commissioner, T.C. Memo 2023-34. SDO CPA — "QSBS Guide 2026" (Jan 2026). Davis Wright Tremaine — "QSBS Just Got a Major Upgrade" (July 2025). BDO — "Have Qualified Small Business Stock? Consider Section 1202 as Part of Your Estate and Trust Planning" (Aug 2025).

Rule 10b5-1 / insider selling. Bass Berry & Sims, Securities Law Exchange — "(Insider) Trading under a Rule 10b5-1 Plan" (July 2025). Candor — "Rule 10b5-1 Trading Plans: Guide for Public Company Executives in 2025" and "10b5-1 Cooling-Off Period" (May 2025). Morgan Stanley at Work — "Demystifying 10b5-1 Plans" (2025). Charles Schwab — "Understanding Rule 10b5-1 Plans" (Jan 2026).

This piece is general educational analysis, not tax, legal, or financial advice. QSBS eligibility, 10b5-1 requirements, diversification strategy, and tax timing are highly fact-specific and depend on current law, which changes. Figures are illustrative. Consult a qualified tax attorney, CPA, and financial advisor before acting.