What Is an Anti-Dilution Provision?
An anti-dilution provision is a term in preferred stock financings that shields investors from price dilution in a down round, meaning a new issuance at a price per share below what they originally paid. Preferred shares convert into common stock at a conversion price, initially set at the purchase price. When a down round occurs, the provision lowers that conversion price, so each preferred share converts into more common shares than before.
The adjustment compensates earlier investors for the markdown but transfers the cost to holders whose shares carry weaker protection, primarily founders and employees holding common stock. Nearly every venture term sheet includes some form of anti-dilution protection, so the real negotiation is over which formula applies and which issuances, such as option grants under the employee pool, are carved out of the trigger.
How the Adjustment Formulas Work
The dominant formula is the broad-based weighted average, which scales the adjustment to the size of the down round. The new conversion price equals the old price multiplied by (A + B) divided by (A + C), where A is the fully diluted share count before the new issue, B is the number of shares the new money would have bought at the old conversion price, and C is the number of shares actually issued. A small down round therefore produces only a small adjustment.
Full ratchet protection is far harsher: the conversion price resets all the way down to the new issue price no matter how few shares are sold. If an investor paid $2.00 per share and the company later sells even a modest number of shares at $1.00, a full ratchet doubles the investor's as-converted share count. Because the resulting dilution lands almost entirely on common holders, full ratchet terms are rare outside distressed or heavily investor-favorable financings.
Why Anti-Dilution Provisions Matter
These provisions determine how the pain of a down round is distributed. When valuations fall broadly, as they did after the 2021 venture peak, anti-dilution adjustments can meaningfully shrink founder and employee ownership on top of the dilution from the new money itself. Companies sometimes negotiate waivers from existing investors as a condition of a rescue round, precisely because layered ratchets can make the cap table untenable for future hires.
For candidates interviewing in venture capital or growth equity, the broad-based weighted average formula is fair game as a technical question, and you should also be able to explain conceptually why it is gentler than a full ratchet. Reading a term sheet's anti-dilution clause, including its carve-outs and any pay-to-play requirement that conditions protection on participating in the new round, is part of basic deal literacy.
