Valuation and dilution questions: post-money, option pools and SAFE caps

In this article

1. Before you start
2. Why interviewers ask this
3. Valuation and dilution from first principles
4. Worked example
5. Trade-offs and edge cases
6. How to answer it in an interview
7. Common mistakes
8. Follow-up questions
9. Sources

Before you start

This page is part of the investor pitch questions path. For related practice, see how to answer "what is your valuation?", term-sheet negotiation conversation scripts, the metrics deep-dive, due-diligence questions and the data room and the investor Q&A prep sheet template.

Why interviewers ask this

The question separates people who repeat the word "valuation" from people who can compute ownership. In venture, startup finance and corporate-finance rounds, a candidate may be handed a term sheet line such as a raise, a valuation and a pool size, and asked who owns what afterwards.

In banking and private equity interviews the same phrase usually means the diluted share count and whether a deal is accretive or dilutive; both are covered after Step 4.

A weak answer quotes the headline valuation and stops. A strong answer first asks whether the number is pre-money or post-money, then turns it into a percentage. A Staff-level answer also asks where the option pool sits, whether any convertible instruments are outstanding, and whether the round could be a down round. Each of those questions changes the arithmetic, and the interviewer is listening for whether you ask them before you calculate.

Valuation and dilution from first principles

Dilution

Dilution is the fall in an existing holder's ownership percentage that happens when a company issues new shares, because the same number of shares you hold is divided by a larger total.

Option pool

An option pool is a block of shares set aside for future employee stock options, counted in the fully diluted share total so that granting options later does not surprise investors.

Anti-dilution protection

Anti-dilution protection is a term in preferred stock that lowers the price at which the preferred converts into common shares when the company later sells shares at a lower price.

In plain words

Think of a pizza cut into slices. Your slices are your ownership. When the company raises money, it cuts more slices and sells them. The pizza is bigger, but your slices are a smaller part of it. The analogy breaks in one place. A company can also add slices for itself, such as the option pool. Who bears the cost of those slices is negotiated.

In precise terms, valuation sets the price per share. The price per share decides how many new shares a given amount of cash buys. Dilution is the resulting change in each holder's percentage.

Step 1: Pre-money plus new cash equals post-money

Pre-money valuation is the valuation of the company immediately before it receives the investment, and post-money valuation is the valuation immediately after it (Y Combinator, SAFE user guide). Post-money valuation equals pre-money valuation plus the new cash. The guide gives the example that raising 2 million dollars at a 10 million dollar pre-money valuation is the same as raising it at a 12 million dollar post-money valuation.

The investor's ownership is the investment divided by the post-money valuation. For the guide's example that is 2 divided by 12, or 16.67%.¹

Now the trap: if the same "10 million dollars" is meant as post-money, the investor owns 2 divided by 10, which is 20%, so the founders are diluted 3.33 points more.¹ The number alone never tells you which one is meant, so you ask. You now know the base arithmetic; the next step shows how one clause moves the price without moving the headline.

Step 2: The option pool shuffle moves dilution onto existing holders

The option pool shuffle is the practice of creating or enlarging the employee option pool before the new money arrives, so the pool counts inside the pre-money valuation. Because the pool shares sit in the share count that sets the price per share, the price per share falls, and only existing holders bear the cost.

Take an illustrative company with 8,000,000 founder shares, a pre-money of 8 million dollars, a raise of 2 million dollars and a target pool of 10% after the round. The pool-share formula from Glencoyne gives 1,142,857 pool shares, so 9,142,857 shares share the pre-money and the price is 0.875 dollars a share. The investor buys 2,285,714 shares for 20%.¹

The founders end with 70%. Their effective pre-money is 0.875 dollars times 8,000,000 shares, which is 7.0 million dollars, not the 8 million dollars on the term sheet.¹ If the same pool were created after the money and diluted everyone, the founders would keep 72% and the investor 18% (illustrative).¹

Step 3: A post-money SAFE fixes the percentage until the priced round

A Simple Agreement for Future Equity (SAFE) is a short contract an investor signs to fund a startup now in exchange for the right to shares later, and it converts into shares automatically when the startup raises a priced round (Y Combinator, the SAFE). With a post-money SAFE, the ownership sold equals the investment divided by the post-money valuation cap. A 1 million dollar SAFE at a 6.7 million dollar cap sells about 15% (Y Combinator, the SAFE).

A cap is a ceiling on price, not a final valuation. The SAFE holder gets the better of two outcomes: the ownership the cap implies, or the shares its money buys at the price the new investors pay. If the priced round values the company below the cap, the cap does not apply.

The cap is "post" all the money raised on SAFEs, but not post the priced round. The SAFE percentage is therefore diluted by the new money and by any option-pool increase in that round. Because a post-money SAFE sells the investment divided by the cap, the SAFEs together can never exceed 100%: total SAFE money must stay well below the cap, or founders are left with little or nothing before the priced round.

Step 4: Anti-dilution adjusts the conversion price in a down round

A conversion price is the price at which one preferred share converts into common shares. Anti-dilution protection lowers it when the company later sells shares at a lower price, a down round, so each preferred share converts into more common shares. New shares sold at a higher price still dilute but do not trigger it.

Broad-based weighted average is the market-standard form and the default in the National Venture Capital Association (NVCA) model term sheet, according to Montague Law. Lever Venture also calls it market-standard. Montague Law writes the formula as: new conversion price equals the old conversion price times (outstanding shares plus new money divided by the old conversion price) divided by (outstanding shares plus new shares issued).

Call the outstanding shares A, the shares the new money would have bought at the old price B, and the shares actually issued C. The new price is then the old price times (A + B) divided by (A + C). Read the definitions in the actual charter, because they vary by document. A full ratchet instead resets the price to the new round's price whatever the size of the round.

1 · Pre plus cash2 · Pool shuffle3 · SAFE cap4 · Down roundReplay

Step-by-step description

1. Post-money is pre-money plus cash.
2. A pre-money pool lowers the price.
3. The cap is a ceiling on price.
4. Anti-dilution lowers the conversion price.

• Post-money valuation equals pre-money valuation plus the new cash.
• A pool created before the money lowers the price per share for existing holders.
• A SAFE cap is a ceiling on price, not a final valuation.
• Anti-dilution lowers the conversion price when shares are sold at a lower price.

Banking version: diluted shares by the treasury stock method

The treasury stock method is the standard way to count the shares that in-the-money options add to a company's share count: assume the holders exercise, the company uses the cash to buy back shares at the current price, and only the net new shares count. Take an illustrative company with 100 million basic shares (illustrative), 10 million options with a strike price of 20 dollars and a share price of 50 dollars.

Exercise brings in 200 million dollars, which buys back 4 million shares, so 6 million net new shares are added and the diluted count is 106 million.¹ If the strike price were at or above the share price, the options would add nothing. Equity value is then 106 million times 50 dollars, or 5,300 million dollars, and enterprise value adds debt and subtracts cash; with 1,000 million dollars of debt and 400 million of cash (illustrative) it is 5,900 million.¹ An in-the-money convertible bond is treated as converted: add its shares and drop its debt.

Banking version: accretion and dilution in a deal

An accretive deal is one in which the buyer's earnings per share rise after it, and a dilutive deal is one in which they fall. Suppose an illustrative buyer earns 500 million dollars on 100 million shares, which is 5.00 dollars a share, and buys a target earning 100 million dollars by issuing 15 million new shares. Combined earnings of 600 million over 115 million shares give 5.22 dollars, an accretion of 4.35%.¹ At 20 million new shares the result is exactly 5.00 dollars, the break-even. This sketch ignores synergies, financing costs and purchase accounting, which a full model adds.

Worked example

Start with the plain round: an 8 million dollar pre-money plus 2 million dollars of new cash is a 10 million dollar post-money, so the investor owns 20% and existing holders keep 80%.¹ Then add the pool shuffle and the founders fall to 70%, as in Step 2.

Text description of the diagram

• Founders keep 80% with no pool, 72% when the pool is created after the money, and 70% when it is created before.
• Then add the pool shuffle and the founders fall to 70%.

Founders keep 80% with no pool, 72% when the pool is created after the money, and 70% when it is created before.¹

Now a SAFE case from the Y Combinator guide (pp. 11–12). Founders hold 90%, outstanding options 8% and the unissued pool 2%. A 500,000 dollar SAFE at a 5 million dollar post-money cap sells 10%, leaving founders 81%, outstanding options 7.2% and the unissued pool 1.8%.¹

The guide's fully worked Series A example has SAFEs of 200,000 dollars at a 4 million dollar cap and 800,000 dollars at an 8 million dollar cap, then 5 million dollars at a 15 million dollar pre-money. The pre-money includes a 10% post-closing pool and the SAFE conversion shares. With 10,000,000 pre-financing fully diluted shares, the Company Capitalization is 10,000,000 divided by 85%, or 11,764,705, and the pool increase of 1,695,000 shares sets a price of 1.1144 dollars.¹ These inputs and the share counts are from the guide's Appendix II, Example 1 (PDF pp. 19–21).

Pro rata can be back-solved the same way, with illustrative numbers. Suppose SAFE holders own 15% and have pro rata rights, and the outside new investors are to take 25% of the company. The goal is the SAFE holders' pro rata purchase.

• Step A: the SAFE holders buy 15% of the round, so the outside investors buy the other 85%.
• Step B: outside investors take 25% of the company, so the whole round is 25% divided by 85%, or 29.41% of the company.
• Step C: the SAFE holders' purchase is 29.41% minus 25%, or 4.41% of the company.
• Step D: assume, for simplicity, that no pool existed before and it is topped up to 10%. That adds 10 points, so existing holders are diluted by 29.41% plus 10%, or 39.41%.¹

Trade-offs and edge cases

Every term in a round trades one party's protection against another's price. A pre-money pool favours the new investor and costs existing holders. A post-money pool spreads the cost to the investor too, which is why investors resist it. Say which pool you mean: "10%" can be a share of the pre-money or of the fully diluted post-money count.

Anti-dilution trades the investor's downside protection against the founders' ownership in a bad round. The two forms differ sharply in size.

Text description of the diagram

• Broad-based weighted average gives 1.00 times 11 divided by 12, or 0.9167 dollars.
• A full ratchet resets the price to the new round's price whatever the size of the round.

In an illustrative down round, 10 million fully diluted shares, an old price of 1.00 dollar and 1 million dollars raised at 0.50 dollars, the new shares C are 2 million and B is 1 million. Broad-based weighted average gives 1.00 times 11 divided by 12, or 0.9167 dollars. A full ratchet gives 0.50 dollars, so each preferred share converts into 2.0 common shares instead of about 1.09.¹ "Broad-based" means the denominator counts all fully diluted shares, including options and the unissued pool, and a broader denominator means a smaller adjustment (Montague Law).

Edge cases: when the SAFE price implied by the cap is below the round price, the SAFE converts at the cap price and gets more shares; when the round price is lower than that, it converts at the round price. Several SAFEs with different caps stack, so build the table, not the shortcut. For formal definitions of the weighted-average terms, check the NVCA model legal documents themselves.

How to answer it in an interview

The numbers in this answer are illustrative and computed in the data script.¹ The spoken structure: ask pre or post, compute the percentage, name the pool, then name the convertibles.

Common mistakes

• "We raised at a 10 million dollar valuation, so the investor owns 20%." (wrong) The percentage depends on pre-money or post-money. (right) "Is that pre-money or post-money? Then I divide the investment by post-money."
• "The option pool dilutes everyone equally." (wrong) That holds only if it is created after the money. (right) "A pre-money pool is borne by existing holders and lowers their effective pre-money."
• "A SAFE cap is the company's valuation." (wrong) A cap is a ceiling on price. (right) "The SAFE converts at the cap or at the round price, whichever gives the holder more."
• "Pro rata means no dilution." (wrong) The pool increase in the same round can still dilute the investor. (right) "Pro rata lets you buy into the next round to keep your percentage, but the pool increase in that round can still dilute you."
• "Anti-dilution protects against all dilution." (wrong) It adjusts the price only when shares are sold lower. (right) "It triggers in a down round, and new shares at a higher price still dilute."

Follow-up questions

What is the difference between pre-money and post-money valuation?

Pre-money is the value immediately before the investment and post-money the value immediately after it. In an interview, ask which one is meant: 2 million dollars into "10 million" is 16.67% if pre-money and 20% if post-money.

What is an option pool shuffle?

An option pool shuffle is creating the employee option pool before the investment so it sits inside the pre-money. The effect to quote is the founders' effective pre-money, 7 million dollars instead of 8 in the worked example.

Does a SAFE valuation cap equal the company's valuation?

No. A cap only limits the conversion price. If the round prices below the cap, the SAFE converts at the round price, so the cap never leaves the holder worse off.

How does anti-dilution work in a down round?

The size of the adjustment is what interviewers probe: in the illustrative round, weighted average gives 1.09 common shares per preferred share and a full ratchet gives 2.00.

How do you calculate diluted shares outstanding?

Start from basic shares and add the net new shares from in-the-money options using the treasury stock method, plus any in-the-money convertibles as if converted. In the illustrative example, 100 million basic shares and 6 million net option shares give 106 million.¹

Is a deal accretive or dilutive?

Compare the buyer's earnings per share before the deal with the combined earnings per share after it, counting any new shares issued. In the illustrative example, 15 million new shares lift earnings per share from 5.00 to 5.22 dollars, so the deal is accretive.¹

Sources

1. Post-Money SAFE User Guide and Quick Start Guide — Y Combinator (form v1.2), 1 Feb 2023
2. The SAFE: the standard way startups raise money — Y Combinator, 26 Oct 2026
3. NVCA Model Legal Documents — National Venture Capital Association, 26 Oct 2026
4. Series A Preferred Stock Term Sheet — Montague Law, 26 Oct 2026
5. Term Sheet Guide for Life Sciences Founders — Lever Venture, 26 Oct 2026
6. Option pool math and dilution — Glencoyne, 26 Oct 2026