Convertible Preferred Stock
Also known as Convertible Preferred, Convertible Preferred Shares
Convertible preferred stock is preferred equity that can be exchanged for common stock at a defined conversion ratio, either at the holder's election or automatically at events such as a qualified IPO. It is the standard instrument used in venture priced rounds because it combines downside protection (liquidation preference) with upside participation (conversion).
Formula
Conversion Ratio = Original Issue Price / Current Conversion Price- Original Issue Price
- Price per share paid by the investor at the time the series was issued
- Current Conversion Price
- Conversion price after any anti-dilution adjustments; starts equal to Original Issue Price
In depth
Every share of venture preferred stock has a conversion price that starts equal to the price the investor paid. The conversion ratio is original issue price divided by current conversion price. At issuance the two are equal, so the ratio is 1:1. Anti-dilution provisions reduce the conversion price after a down round, which raises the ratio and gives the investor more common shares on conversion without any new cash.
The holder picks conversion at exit by running both math paths. Path A: take the liquidation preference (a fixed dollar amount). Path B: convert to common and share in proceeds pro rata. Whichever is larger wins. The Certificate of Incorporation makes this a unilateral right of the holder, exercisable on or before any liquidation event. At IPO, the underwriters and the Certificate of Incorporation force conversion because the public market can only price one class of stock.
Why it matters
The convertibility is what makes venture preferred equity rather than debt. Without conversion, the investor would only ever recover their preference plus a small dividend. Conversion is how the investor captures the asymmetric upside that the venture model requires. From a cap table modeling perspective, every fully diluted ownership table assumes all preferred is converted to common at the current conversion ratio, which is why post-money ownership percentages are quoted on an as-converted basis.
Worked example
An investor buys 1,000,000 shares of Series A at $4.00 (so $4M invested). Original conversion price = $4.00. Conversion ratio = 1:1.
A later down round prices Series B at $2.00 with broad-based weighted-average anti-dilution. The Series A conversion price drops from $4.00 to (illustratively) $3.20. The new conversion ratio:
Conversion Ratio = $4.00 / $3.20 = 1.25
The investor's 1,000,000 preferred shares now convert into 1,250,000 common shares. They did not write a new check. The extra 250,000 shares come from anti-dilution alone and dilute common holders (founders, employees) on conversion.
Frequently asked
When does convertible preferred actually convert?
Two paths. Optional conversion at the holder's election (any time, typically used at IPO to participate pro rata in offering proceeds). Mandatory conversion on a qualified IPO above a defined threshold (often a price equal to 2-3x the original issue price and a minimum offering size, e.g. $50M gross) or on the vote of a defined majority of the series. Most preferred converts at IPO because conversion lets the holder share in the upside rather than just take the preference.
What is the conversion ratio at issuance?
1:1 at the time of issuance. One share of Series A preferred converts into one share of common. The ratio only moves up (more common per preferred) when anti-dilution kicks in following a down round, which lowers the conversion price.
Why convert when the liquidation preference would pay more?
Only convert when conversion economics beat the preference. At low exits, holding the preference wins. At high exits, the preferred's pro rata share of total proceeds as common is larger than the fixed preference. The breakeven is where (number of common-equivalent shares × price per common) equals the liquidation preference amount.
Can the company force conversion?
Yes, via the mandatory conversion clauses in the Certificate of Incorporation. Common triggers: qualified IPO (price and size thresholds), majority vote of the preferred class, or the lapse of a specific date. Without a mandatory trigger, a preferred holder could block an IPO by refusing to convert.