Anti-dilution protection

Anti-dilution protects preferred investors when the company later sells shares cheaper than they paid. Ordinary dilution from raising new money always shrinks everyone's percentage — that is not this clause. You can raise a huge up round and go from 20% to 15% with no anti-dilution event. You can raise a tiny down round and trigger a brutal ratchet. Price path matters, not just share count.

Preferred converts into common at a conversion price. Anti-dilution lowers that price on a cheaper primary issuance, so each preferred share becomes more common. Ownership shifts from common (and unprotected holders) toward the protected preferred.

Read the formulas first, then come back here for carve-outs, modeling and what to do once the clause is signed.

Step	Concept	What it answers
1	Full ratchet	What if the old price resets all the way to the new one?
2	Weighted-average anti-dilution	How does the market formula share the pain?
3	Pay-to-play	What if yesterday's investor will not follow on?

Why the clause exists

Series A buys at $4.00. Eighteen months later Series B is $1.00. New investors get 4× the shares per dollar. Absent anti-dilution, Series A's percentage shrinks and their "price" looks permanently wrong. VCs argue they took early risk and deserve a reset. Founders argue that ratchet-style resets punish the team for raising survival capital. The market compromise is weighted average.

Certificates usually carve out option grants at 409A fair value, shares in a vetted acquisition, conversions of already-outstanding preferred, notes or SAFEs, and sometimes small strategic issuances. Without carve-outs, hiring could theoretically trigger the clause. Confirm the list looks like NVCA, not a blank page.

Modeling a down round

Compute three cap tables: (1) no anti-dilution, (2) weighted average as drafted, (3) full ratchet. Then decide which waivers to request. Effects you will see:

Existing preferred get more as-converted ownership.
Common and option holders dilute more than the headline "new investor owns X%" suggests.
New investors may require prior preferred to waive or amend the clause as a closing condition — a recap negotiation.
Employee refresh needs grow because grants are underwater.

You cannot undo a signed clause with optimism. You can raise at a higher price so it never fires; structure a bridge that counsel confirms is carved out or waived (in writing); negotiate a recap; or use pay-to-play so non-participants lose protection. Each path has governance cost. The wrong path is pretending the formula will not matter.

Trade-off

If the down round is small and weighted average barely moves CP, live with it. If you need a large primary at a steep discount, new investors may refuse to close unless prior preferred waive. Pay the political cost early rather than dying on the runway with a blocked financing.

Cap tables often show preferred share counts unchanged and the new conversion price in a footnote. When someone says "Series A still has two million shares," ask "at what conversion price?"

If you hold a large grant, ask whether the last financing was up or flat — that tells you whether this clause is asleep. Pair with employee equity and down rounds.

Common mistakes

Confusing this with ordinary dilution. New money always dilutes. Anti-dilution is the extra rewrite when price falls.
Not modeling all three cases before a distressed close.
Assuming option grants are harmless without reading carve-outs.

Key takeaways

Anti-dilution lowers preferred conversion price when cheaper shares are issued.
Full ratchet is harsh and non-market; broad-based weighted average is the standard.
Always model the clause explicitly in a down round, and confirm carve-outs exist.
Pay-to-play ties leftover protection to following on.