What Is a Conversion Premium?

What Is a Conversion Premium?

4 Min.

The concept of a conversion premium pertains to the added value inherent in a convertible security, arising from its conversion option. This premium emerges because, upon conversion, the investor's ownership in equity shares surpasses their prior bond ownership. Traders employ convertible arbitrage strategies to exploit surplus conversion premiums within the market. Notably, the conversion premium plays a pivotal role in calculating a convertible security's payback period.


A conversion premium signifies the excess value of a convertible security compared to the present market worth of the common stock it can potentially transform into. This premium is quantified in dollars and delineates the disparity between the convertible's price and the higher of its conversion or straight bond value. It serves as a pivotal metric for investors evaluating the financial advantage of converting their securities into common stock, offering a critical gauge for decision-making in this regard.

Exploring Conversion Premium

Convertible securities encompass various financial instruments, including bonds and preferred shares, offering the option to exchange them for a predetermined quantity of common shares at an agreed-upon price. Upon maturity of convertible bonds, they can be redeemed at either their face value or the prevailing market value of the underlying common shares, whichever proves higher. The decision to convert can be at the discretion of the investor or enforced by the issuing company.

Consider convertible bonds as an illustration. These are unsecured debt securities that can be transformed into the corporate issuer's common stock during a specified timeframe, subject to the bondholder's choice. The bond's trust indenture specifies the conversion ratio, indicating how many shares each bond can be converted into. For instance, with a conversion ratio of 40 (or 40 to 1), each bond, with a par value of $1,000, can be converted into 40 shares of the issuing company.

Alternatively, the trust indenture might express the conversion feature as a conversion price, determined by dividing the bond's face value by the conversion ratio. If the share price is $25, then the conversion ratio can be derived as follows: $1,000 par value divided by $25 equals 40 shares.

Transforming Convertible Securities

Upon issuance of a bond, the excess of its price over the conversion price is denoted as the conversion premium. This premium assesses the prevailing market price in comparison to the greater the conversion value or the straight-bond value. The straight-bond value represents the convertible's worth without the conversion option, while the conversion value is determined by multiplying the conversion ratio by the current market price of common stock.

For instance, consider a scenario where a company releases a convertible bond, exchangeable in the future for 50 shares of common stock, with the common stock currently valued at $20 per share. In this case, the conversion value amounts to $1,000, calculated as 50 shares multiplied by $20. The conversion premium, conversely, signifies the additional value the bondholder holds above the conversion value. If the bond is currently trading at $1,200, the calculation of the conversion premium is $1,200 minus $1,000, resulting in $200.

Understanding Conversion Premia and Payback

The conversion premium serves as a crucial factor in determining the bond's payback period, representing the duration required for the bond to accumulate the conversion premium along with all stock dividends throughout the period. Additionally, the cash-flow payback period signifies the time needed for the convertible to generate interest equal to the conversion premium and stock dividends, assuming the purchase of the specified number of shares according to the conversion ratio, rather than the convertible. The formula for the cash-flow payback period is:

Cash-Flow Payback Period = [Conversion Premium / (1 + Conversion Premium)] / [Current Yield - Dividend Yield / (1 + Conversion Premium)]


In summary, the concept of a conversion premium is a vital component of convertible securities, signifying the added value stemming from their conversion option. This premium is instrumental in calculating the payback period and plays a pivotal role in investment decisions. Convertible securities, including bonds and preferred shares, offer investors the option to exchange them for common shares at predetermined terms, with the conversion premium serving as a key determinant of their worth. Understanding conversion premiums is essential for investors looking to optimize their investment strategies and make informed choices in the complex world of convertible securities. Lastly, traders often leverage conversion premiums to their advantage, underscoring their significance in financial markets.

Conversion Premium
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