What it means
A convertible bond may be exchanged for a stated number of the issuer's common shares, so its buyer can estimate how much each resulting share effectively costs using the bond's market price rather than its original face amount. If a bond trades at $1,200 and converts into 20 shares, parity price is $60 per share.
If the common stock trades at $55, the immediate share package is worth $1,100, below the bond's quoted market value. At a $65 stock price, those 20 shares are worth $1,300.
Comparing $1,300 with $1,200 suggests that converting or another arbitrage transaction deserves investigation, not that $100 can be collected without cost or restriction. The conversion ratio is essential, because a corporate action or contract adjustment may change how many shares are delivered and an old ratio can produce a wrong parity calculation.
The contractual conversion price usually divides a bond's face amount or specified conversion amount by its share ratio. For $1,000 face value and 20 shares, it is $50, even when the same bond's market price of $1,200 implies a $60 parity price.
A person who paid $900 for the bond has yet another cost basis, and the market parity price does not calculate that holder's realised gain, tax basis or historical return. The convertible can trade above its immediate conversion value because it retains future equity upside, coupons and some debt characteristics.
Converting too soon can surrender those rights and be worse than selling the bond for cash. The SEC's Investor.gov explains that standard convertible securities often use a fixed formula but some arrangements tie share count to a fluctuating stock price.
In a variable-ratio security, parity must be recalculated under the applicable formula at each relevant quote, and falling stock prices that yield more shares can create substantial dilution for existing shareholders. A manager reviewing capital structure needs the issuer's worst-case share count, not only a holder's current parity price.
A preferred share with a conversion feature can use the same idea: divide its current price by the common shares it yields, remembering the foregone preferred dividend and liquidation priority. For a manager, the parity calculation is an initial screen.
Check current contract terms, expected shares, executable prices, income rights, issuer call provisions and trading costs before telling an investor to convert.
In practice
Real-world examples.
Example
A convertible bond quotes at $1,200 and delivers 20 shares. Its conversion parity price is $60; a $55 common-share quote makes immediate conversion worth $1,100.
Example
The same bond has $1,000 face value. Its contractual conversion price is $50, even though its current market-price parity is $60.
Example
After an adjustment, the bond delivers 25 shares instead of 20. At a $1,250 bond quote, parity price is now $50 per share, so the old ratio would overstate it.
Formula
Calculation
Conversion parity price = current all-in price of convertible security / shares delivered on conversion. A $1,200 bond yielding 20 shares implies $60 per share. Conversion value = stock price x 20; at $55 it is $1,100. Contractual conversion price using $1,000 face amount is $1,000 / 20 = $50. These are distinct measures, and accrued interest or variable ratios may alter the inputs.
The premium over conversion value shows how much extra the market pays for the bond's other rights: ($1,200 - $1,100) / $1,100 = $100 / $1,100 = 9.1% at a $55 share price. That premium reflects the bond's coupons, its debt protection and its remaining option value.Case study
Seen in the real world.
Fictional case: A fund owns a convertible bond with $1,000 face value and a right to receive 20 common shares. The bond quotes at $1,200 and the shares at $62, making the share package worth $1,240 and the market parity price $60. Its analyst checks whether the bond quote excludes accrued interest, whether the shares can be sold at $62 in the required size, and whether conversion forfeits a pending coupon. The issuer has also announced a possible call, so timing matters.
The fund compares sale and conversion proceeds net of costs before acting, while the issuer models dilution if many bonds convert. The analyst also runs the opposite scenario. If the shares fell back to $55, the 20-share package would be worth only $1,100, which is $100 below the bond quote, and conversion would give up the bond's remaining protections. The committee therefore records the bond's value as debt and treats conversion as an option, not an obligation.
Watch out
Common mistakes.
- Dividing the bond's face value by shares and calling it current market parity price.
- Assuming a share quote above parity makes conversion better than selling a convertible with remaining option value.
- Using an outdated fixed ratio when contract adjustments or market-linked conversion terms change the share count.
Questions
People also ask.
How does parity price differ from conversion value?
Parity price is convertible market price per share received; conversion value is the current market value of the shares received.
Does parity price use what I originally paid?
No. It uses the relevant current convertible price for a market comparison; your cost basis is separate.
Can the ratio change?
Yes. Contract adjustments or market-linked formulas can change the number of shares delivered.
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