What it means
A convertible bond is a loan that the holder can swap for a fixed number of shares. The conversion price is the effective share price at which that swap makes sense, and while the shares trade above it the bond moves with the equity.
When the shares collapse, the conversion right is deep out of the money, meaning it would be irrational to exercise it, and the bond is described as busted. The label matters because it changes what drives the price.
A healthy convertible is sensitive to the share price and to volatility, while a busted one is sensitive to interest rates and to the issuer's ability to repay at maturity. The same security can move from one regime to the other without a single term of the contract changing.
For the issuer, a busted convertible is a warning about refinancing. The company sold the bond expecting investors to convert into equity so that the debt would disappear from the balance sheet, and that no longer happens.
The cash has to be found instead, which is why busted convertibles often sit behind an equity raise or a distressed exchange. For investors, the attraction is a bond bought below par with a free option attached.
If the business recovers, the conversion right regains value; if it does not, the holder still ranks as a creditor ahead of shareholders. That asymmetry is the whole thesis, and it only works if the credit analysis is done properly.
The nuance is that busted is market shorthand rather than a defined legal status, usually applied when the conversion value is a small fraction of the bond's face value. Watch also for put dates, which let holders demand early repayment, and for change of control clauses, because in a busted convertible those terms matter far more than the conversion ratio.
In practice
Real-world examples.
Example
A biotechnology company raised $200,000,000 of convertibles at a $64 conversion price. After a failed trial the shares trade at $7 and the bonds change hands at 61 cents on the dollar. The holders are now effectively unsecured lenders watching the cash runway rather than equity investors waiting for a rerating.
Example
A retailer's convertible has 18 months to maturity and trades at $830 per $1,000 of par, with a conversion value of $95. The finance team models repaying the full $1,000 in cash rather than assuming conversion, and starts negotiating a replacement facility a year early.
Example
A credit fund buys a busted convertible at $680 because the issuer holds $400,000,000 of cash against $250,000,000 of this debt. The fund is paid $1,000 at maturity, a 47% gain on the bond, with no reliance on the share price recovering at all.
Formula
Calculation
Two figures define the position: Conversion Ratio = Par Value / Conversion Price, and Conversion Value = Conversion Ratio x Current Share Price. The conversion premium is then (Bond Price - Conversion Value) / Conversion Value.
A company issued a convertible bond with a $1,000 par value and a $50 conversion price, giving a conversion ratio of $1,000 / $50 = 20 shares per bond. The shares have since fallen to $8, so the conversion value is 20 x $8 = $160. The bond trades at $720, which reflects what the market thinks the loan alone is worth, so the conversion premium is ($720 - $160) / $160 = 350%. With a 2% coupon the holder collects $20 a year, a current yield of $20 / $720 = 2.8%, and the real return depends entirely on whether the $1,000 is repaid at maturity.Case study
Seen in the real world.
Pelham Robotics is an illustrative, fictional automation company used here to show how a convertible becomes busted. It issued $150,000,000 of five year convertible bonds at a $40 conversion price when its shares traded at $31, fully expecting the shares to pass $40 so the debt would convert into equity.
Two years later a large contract was lost and the shares fell to $6. The conversion value of each $1,000 bond dropped to 25 x $6 = $150, and the bonds traded down to $690 on credit concerns rather than on anything to do with the equity option.
The finance director's problem changed shape overnight. Instead of a conversion that would have removed $150,000,000 of debt, Pelham faced a cash repayment in three years, and in this illustrative scenario it refinanced early with a secured loan at a materially higher coupon plus an arrangement fee, which is the usual price of noticing the problem late.
Watch out
Common mistakes.
- Assuming a convertible bond always converts and the debt therefore never has to be repaid in cash, which is exactly the assumption a busted convertible destroys.
- Valuing a busted convertible with an equity option model, when the price is being set by credit spread, coupon and recovery value.
- Reading a bond price well below par as a bargain without checking whether the issuer can actually fund the repayment at maturity.
Questions
People also ask.
Does busted mean the bond has defaulted?
No, it only means the conversion right is deep out of the money, and the issuer may still be paying every coupon on time.
Can a busted convertible recover?
Yes, if the share price climbs back towards the conversion price the option regains value, which is why some funds buy them as a cheap recovery play.
Why would a company issue convertibles at all?
Because the coupon is lower than on straight debt, so the issuer is selling an equity option to buy a cheaper interest rate, which only looks clever if the shares perform.
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