Convertible arbitrage compares a convertible security with the issuer's stock, credit risk, volatility, and hedge cost.
Convertible arbitrage is a relative-value strategy that typically buys a convertible bond or convertible preferred security and hedges part of the equity exposure by shorting the issuer’s common stock. The goal is to evaluate whether the convertible is cheap or expensive relative to the stock, credit risk, interest rates, volatility, liquidity, and hedge cost.
The strategy is complex and can involve leverage, short selling, derivatives, issuer credit risk, and liquidity risk. It is an educational topic, not a recommendation to buy convertibles or short stock.
A convertible bond can be viewed as a bond plus an embedded equity option. A trader may buy the convertible and short some amount of the issuer’s stock to reduce equity-direction exposure.
This formula is only a starting estimate. Real positions may adjust for borrow cost, call features, coupons, dividends, credit spread, option volatility, liquidity, and the manager’s risk limits.
| Driver | How it can help | How it can hurt |
|---|---|---|
| Equity volatility | More realized volatility can benefit some dynamically hedged positions | Poor hedge timing or transaction costs can erase the benefit |
| Credit spread | A cheap convertible may recover if issuer credit improves | Credit deterioration can reduce bond value even if the stock hedge works |
| Stock borrow | Short stock can hedge equity exposure | Borrow can be unavailable, recalled, or expensive |
| Interest rates | Rates affect bond value and option valuation | Rate moves can change model values and funding costs |
| Liquidity | Tight markets reduce slippage | Stressed markets can widen quotes and make rebalancing costly |
| Deal or call features | Terms can create optionality or protection | Calls, resets, make-whole terms, or forced conversion can change payoff quickly |
Assume a convertible bond can be converted into 25 shares of the issuer’s common stock. A model estimates the convertible’s equity delta at 0.60. A rough hedge would short 15 shares for each bond-equivalent position:
If the stock falls, the short position may gain, but the convertible can also lose value if the issuer’s credit spread widens. If the stock rises sharply, the convertible may gain, but the short position loses and may need to be adjusted. The trade result depends on the whole package, not just one leg.
| Feature | Convertible investing | Convertible arbitrage |
|---|---|---|
| Typical position | Long convertible security | Long convertible plus equity hedge, and sometimes credit or option hedges |
| Main focus | Income, downside profile, and equity participation | Relative value between convertible, stock, credit, rates, and volatility |
| Risk review | Issuer credit, conversion value, call terms, dilution | All convertible risks plus short borrow, hedge slippage, leverage, and liquidity |
| User base | Investors and portfolio managers | Usually specialized managers, hedge funds, or professional trading desks |
Investor.gov’s convertible securities overview explains common conversion features and dilution risks. For public issuers, review SEC filings in EDGAR for the indenture, prospectus, resale registration statements, 10-K, 10-Q, 8-K, and any financing disclosures that describe conversion formulas, resets, caps, and issuer risks.