Anti-dilution protection is a provision embedded in preferred stock that shields investors from the economic impact of a down round. If a company raises future capital at a lower price per share than an existing investor paid, the anti-dilution provision adjusts that investor’s conversion price downward, effectively giving them more shares to compensate for the reduced valuation.
Why Anti-Dilution Exists
Investors pay a specific price for preferred shares based on the company’s valuation at the time of their investment. If the company later raises money at a lower valuation, the earlier investor overpaid relative to the new price. Anti-dilution protection partially corrects this by adjusting the earlier investor’s economics. It is a standard protective provision in virtually every venture capital term sheet.
From the founder’s perspective, anti-dilution protection is the cost of raising preferred equity. The provision does not prevent dilution entirely. It shifts a disproportionate share of the down round’s dilutive impact from the protected investor onto the common shareholders, primarily founders and employees.
The Two Main Formulas
Broad-based weighted average is the industry standard. It adjusts the conversion price based on a formula that accounts for both the lower new price and the relative size of the new issuance compared to the company’s total capitalization. A small down round triggers a modest adjustment. A large down round triggers a larger one. This is considered the most balanced approach.
The formula uses the total number of shares outstanding (broadly defined to include options, warrants, and convertibles) to weight the adjustment. “Narrow-based” weighted average uses a smaller denominator (only outstanding preferred and common), which produces a more aggressive adjustment favoring the investor.
Full ratchet is the most investor-friendly (and founder-hostile) form. It reprices the investor’s shares entirely to the new lower price, regardless of how many new shares are issued. If an investor bought shares at $10 and the company later issues even a small number of shares at $5, the full ratchet converts the investor’s shares as if they had originally paid $5. This can dramatically increase the investor’s share count and severely dilute common holders. Full ratchet is rare in standard venture deals and is typically only seen in distressed situations or highly investor-favorable markets.
Impact on Founders
When anti-dilution provisions trigger, the adjustment creates new shares for the protected investor without any new capital coming in. This additional dilution falls on common shareholders. In a significant down round, the combined effect of new investor dilution plus anti-dilution adjustments for existing investors can reduce founder ownership substantially.
This is one reason down rounds are so painful beyond the headline valuation cut. The mechanical dilution from anti-dilution adjustments often hits harder than the new investor’s dilution itself.
Negotiation Points
Founders should negotiate for broad-based weighted average anti-dilution in every term sheet. Additional negotiation levers include:
- Pay-to-play provisions. Require investors to participate in the down round to maintain their anti-dilution protection. Investors who do not invest lose their adjustment rights.
- Carve-outs. Exclude certain issuances (small strategic rounds, debt conversions) from triggering the anti-dilution provision.
- Sunset clauses. Some founders negotiate expiration dates on anti-dilution protection, though this is less common.
Review the anti-dilution section of any term sheet carefully and model the cap table impact under downside scenarios. Understanding how the provision works in practice, not just in theory, is critical for protecting your ownership through difficult fundraising environments.
Frequently Asked Questions
What is the difference between full ratchet and weighted average anti-dilution?
Full ratchet reprices an investor's shares to match the lower price of the new round, regardless of how many shares are issued. Weighted average considers both the new price and the number of new shares issued relative to the total. Weighted average is far more common and less punitive to founders. Full ratchet is rare in modern venture deals and is considered aggressive.
When does anti-dilution protection get triggered?
Anti-dilution protection triggers when a company issues new shares at a price below what existing preferred investors paid, known as a down round. It does not trigger during option pool expansions, warrant exercises, or stock splits. The protection is specific to new equity financings where the price per share is lower than the protected investor's original price.
Can founders negotiate anti-dilution terms?
Yes. While some form of anti-dilution protection is standard in venture deals, the specific formula is negotiable. Founders should push for broad-based weighted average (the most founder-friendly standard formula) over narrow-based weighted average or full ratchet. Some founders also negotiate carve-outs that exclude certain small issuances from triggering the provision.
