How Equity Dilution Works

Dilution is one of the most misunderstood mechanics in startup financing. When a company raises money by issuing new shares, existing shareholders keep every share they owned — what changes is the total number of shares outstanding. Your slice of the pie gets thinner because the pie now has more slices, not because anyone took shares away from you. Understanding this distinction matters, because dilution is not inherently bad; it is the price of capital.

Pre-Money and Post-Money Valuation

Every priced round starts with a pre-money valuation, the agreed worth of the business before new capital arrives. Add the investment and you get the post-money valuation. The investor's ownership is simply their check divided by the post-money figure. This is why the distinction between a "$8 million pre" and an "$8 million post" deal is not a technicality — on a $2 million raise, the difference is 20% versus 25% of the company.

The Option Pool Shuffle

Investors typically require an employee option pool to be in place before they invest, sized to cover hiring until the next round. The critical detail is when that pool is created. If it is carved out of the pre-money valuation — the market standard — the new shares dilute only the existing shareholders, not the incoming investor. The investor still receives their full negotiated percentage, and founders absorb the entire cost of the pool. Switching the timing setting in Advanced Options shows exactly how many percentage points this convention costs you.

Dilution Is Not the Same as Loss

A smaller percentage of a larger company is frequently worth far more than a larger percentage of a smaller one. A founder who drops from 60% to 48% while the valuation rises from $8 million to $10 million has seen the paper value of their stake increase. The scenario where dilution genuinely destroys value is a down round, where new shares are issued at a lower price than previous investors paid, shrinking both the percentage and the value behind it.

Planning Across Multiple Rounds

Dilution compounds. A founder who gives up 20% in a seed round, 20% in a Series A, and 15% in a Series B does not retain 45% — the rounds multiply rather than add, leaving roughly 54% of their original stake. Layer option pool expansions on top of each round and founding teams commonly land between 10% and 20% by the time a company reaches later-stage financing. Modeling each prospective round before signing a term sheet is the only reliable way to see where you will end up.

What to Negotiate

The headline valuation attracts the most attention, but the option pool size and its timing often move founder ownership by more than a modest valuation bump would. A smaller pre-money pool, a post-money pool, or a pool sized against a realistic hiring plan rather than an inflated one can each be worth several percentage points. Run the scenarios before the term sheet is signed, not after.