How Does Option-Pool Dilution Work?
A larger option pool sets aside more shares for future employees. This reduces existing holders' ownership percentages. If the top-up happens before the round is priced, current holders usually bear it. If it happens after closing, the new investor shares the dilution. The same headline company value can therefore buy a different stake.
This pool adjustment sits alongside the dilution created by the financing itself. Showing the two separately reveals how much ownership changed because the company sold shares for cash and how much was reserved for future employees.
Carta's Q1 2025 private-market report found median Series A dilution of 17.9%, down from 20.9% a year earlier. That Carta figure measures total round dilution. The option pool is only one component. It is useful here because it shows that the financing already moves ownership materially before any separate pool increase is considered.
What an Option Pool Represents
An option pool is equity the company is allowed to use for awards. Some may already be promised to staff or advisers. Only the unused part remains available for new hires.
- Granted awards: Options or other awards already promised to recipients.
- Available pool: The unused reserve that remains available for future grants.
- Fully diluted capitalization: This is the share count used to measure ownership. Under the deal's definition, it may include issued shares, existing awards, the unused pool, warrants and convertibles.
Carta describes about 10% of company shares as a common rule of thumb, while noting that actual pools vary. The hiring plan explains how much equity the company may use and how long that reserve could last.
Plan size differs from unused hiring capacity. A company can have a 12% plan with only 3% left after existing grants. That remaining 3% is what the company can still offer, so any top-up depends on how far it falls short of the hiring plan.
Where the Dilution Enters
A “10% post-close pool” describes the intended size after the round. The point at which its new shares enter the fully diluted count determines who gives up ownership to create it.
A company with 10 million existing shares and a $40 million pre-money valuation is raising $10 million. Creating a 10% available post-close pool before the round is priced leaves the investor with 20%, the pool with 10% and existing holders with 70%. The pre-money addition spreads the same valuation across more shares, lowering the financing price from $4.00 to $3.50 per share.
At the same $40 million pre-money valuation and $10 million investment, a 10% post-close available pool produces different ownership depending on its timing. A pre-money top-up leaves existing holders with 70% and the new investor with 20%. A post-money top-up leaves them with 72% and 18%. The example excludes convertibles, warrants, outstanding awards and deal costs.
Who Absorbs the Pool Top-Up?
Moving the same 10% pool from pre-money to post-money shifts 2 percentage points of post-close ownership from the new investor to existing holders in this simplified example.
View calculation data and assumptions
| Item | Pre-money top-up | Post-money top-up |
|---|---|---|
| Existing shares before financing | 10,000,000 | 10,000,000 |
| Pre-money valuation | $40,000,000 | $40,000,000 |
| New investment | $10,000,000 | $10,000,000 |
| Target available pool after closing | 10% | 10% |
| New pool shares | 1,428,571 | 1,388,889 |
| Financing price per share | $3.50 | $4.00 |
| New investor shares | 2,857,143 | 2,500,000 |
| Existing-holder ownership | 70% | 72% |
| New-investor ownership | 20% | 18% |
| Available-pool ownership | 10% | 10% |
How Hiring Needs Translate Into a Pool
The expected hires before the next round or major goal create demand for equity grants. The unused pool covers some of that demand already. The gap between the two explains how many extra shares may be needed.
- Planned roles: Expected hiring dates, seniority, function and sometimes location affect the amount of equity likely to be offered.
- Grant estimates: Comparable pay data gives a reference, while company stage, cash pay and scarcity of candidates can change the grant needed for a role.
- Refresh and promotion grants: Existing staff may need more equity as their roles grow or earlier awards vest.
- Unused balance: The existing reserve supplies part of the hiring budget, leaving only the additional top-up to change the financing share count.
- Time horizon: A pool covering 24 months of hiring serves a longer plan than one expected to last 12 months.
A small buffer can allow for an unplanned senior hire or a tougher hiring market. A large buffer needs a clear reason. Otherwise it dilutes existing holders without a link to people the company expects to hire.
How the Agreed Terms Appear in the Ownership Model
The term sheet records the agreement, and the pro forma translates it into shares and ownership after closing. The fully diluted share count connects the two.
- A "10%" pool can mean the total available balance after closing or a new 10% issue in addition to the existing reserve. Those definitions produce different dilution.
- Awards already counted as outstanding shares differ from equity still available in the pool.
- SAFEs, notes, warrants and accrued interest affect the share count under their own conversion terms.
- A calculation using only common shares differs from one including all securities on an as-converted, fully diluted basis.
- Board, shareholder, equity-plan and securities-law requirements determine the steps needed to make the change effective. Qualified local counsel can explain which apply.
Dilution also compounds across events. A holder that starts at 5%, then absorbs 15% dilution and later 20% dilution, retains 3.4% before any pro rata investment: 5% multiplied by 85% and then by 80%. Adding 15% and 20% would overstate the loss because the second event acts on an already smaller stake.
What the Pool Means for the Investor's Return
For an LP, co-investor or secondary buyer, the pool links hiring to returns. The company needs equity to build its team. The investor needs to retain enough ownership for the return case to work.
- Issued shares, award status, unused grants, convertibles, warrants and share classes together explain the current fully diluted base.
- Grants used and forfeitures returned change how much capacity remains to meet the hiring forecast.
- Later rounds and further pool increases can reduce ownership again, especially when the investor does not take up pro rata rights.
- Exit ownership: The stake remaining after later rounds depends on how much dilution occurs at each stage.
- Approval rights determine who can expand the pool, while timely cap-table updates reveal its effect to investors.
The opening percentage is only the starting stake. Hiring and later rounds can reduce it, while maintaining it may require more cash from the investor. Both changes affect the eventual return.
Including the Hiring Plan in the Ownership Calculation
The option pool belongs in the main deal model because hiring plans affect the price paid for ownership.
- Operating plan: Expected hires explain the purpose and size of the equity reserve.
- Ownership calculation: Price, security terms, convertibles and the pool all contribute to the same fully diluted table.
- Ownership at exit: Later rounds and pool increases can have a larger effect than the opening cap table suggests.
A pool sized for realistic hires gives its dilution a clear purpose. Connecting those grants to the ownership model shows how staffing plans affect the investor's eventual share of the company.
Frequently Asked Questions
Does an option pool dilute investors?
Yes. Timing affects who bears most of the dilution. A pool set up or expanded before the round is priced normally dilutes existing holders. A top-up after closing generally dilutes everyone, including new investors, unless the documents say otherwise.
Is a 10% option pool standard?
It is a common example rather than a fixed requirement. The unused balance covers part of the hiring plan, while expected grants and refresh awards consume it over time. Company stage and the likely date of the next financing affect how much reserve is useful.
Do ungranted options count as dilution?
They may count in the fully diluted denominator used to price a financing even though no employee holds them yet. The exact treatment depends on the transaction definition and legal documents.
How should an investor model option-pool dilution?
The model connects the current fully diluted cap table to the extra pool shares, convertible claims and new investor shares. Later rounds then show how ownership changes with or without pro rata investment. Legal and tax consequences depend on the investor and can be explained by qualified advisers.