Dilution
Also known as: Equity Dilution, Ownership Dilution
The reduction in existing shareholders' ownership percentage caused by the issuance of new shares.
Full Definition
Dilution occurs every time a company issues new equity — at each funding round, when options vest, and when convertible instruments convert. Founders and early investors are diluted with each new round. Anti-dilution provisions protect investors (but not founders) from dilution if the company raises at a lower valuation in a future round. Managing dilution requires balancing the capital needs of the business against the equity retention needed to keep founders and early team members motivated.
Example
A founder who owns 80% of the company before a seed round may own 55% after the seed, 38% after the Series A, and 25% after the Series B — reflecting the cumulative dilution from each round plus option pool expansion.