Dilution is one of those concepts every new angel nods along to and few can actually compute on the spot. Here’s the plain-English version, with the math made visible instead of hand-waved.
The core idea in one sentence
Every time a company issues new shares — to a new investor, to an option pool, to a co-founder — the total number of shares grows, and your existing shares represent a smaller slice of that larger total. You don’t lose shares. You lose percentage.
A worked example
Say a company has 10,000,000 shares outstanding and you own 100,000 — a 1% stake. It raises a new round, issuing 2,500,000 new shares to the incoming investor. Total shares outstanding are now 12,500,000. You still own 100,000 shares, but that’s now 100,000 ÷ 12,500,000 = 0.8%. You didn’t sell anything. The pie got bigger, and your slice, unchanged in absolute size, shrank as a percentage.
Why dilution isn’t automatically bad
0.8% of a company that just raised growth capital and is now worth meaningfully more can easily be worth more in dollar terms than 1% of the smaller company before the round — if the capital raised actually increases the company’s value by more than the dilution costs you. That’s the entire judgment call behind every follow-on decision: is this round dilutive to your percentage, but accretive to your dollars?
The question to ask before every new round
Not “how much will I be diluted” — that’s almost always answerable and almost never the real question. Ask: “what is this capital being used for, and does that use plausibly grow the company’s value by more than my percentage shrinks?” That reframes dilution from a loss to evaluate into a trade to underwrite.
New to angel investing and want the rest of the vocabulary demystified the same way? Our Venture & Startups quiz deck is a good next stop.
