As an investor, you’re typically given a choice: You can buy shares of stock, which makes you part owner of the underlying company, or you can buy bonds or other fixed-income securities, in which case you’re loaning the company money (and they’ll pay you interest).

　　But what if you could buy a bond, earn some interest, and then trade that bond for shares in the company’s stock if its value were to rise significantly?

　　What is a convertible bond?Convertible bonds are a type of corporate debt security that can be converted into a fixed number of shares of the issuer’s common stock. In certain market conditions, they may offer shareholders a more favorable return (relative to risk) versus buying the stock alone, at a lower cost to the company than issuing debt or equity. The mix of current income and potential for capital appreciation is attractive, particularly in volatile markets. Convertibles may also offer holders some protection in bankruptcy, which appeals to venture capitalists and other early-stage investors.

　　These are complex securities that aren’t issued nearly as often as stocks or bonds. And if you’ve never heard of them until now, that’s OK; most convertible bond buyers are institutional investors. But there are a few exchange-traded funds (ETFs) and mutual funds that focus on convertible securities. For example, as of 2024, the two largest convertible ETFs are the SPDR Bloomberg Convertible Securities ETF (CWB) and the iShares Convertible Bond ETF (ICVT).

　　How convertible bonds work and an exampleWhen companies need to raise money, they typically either issue more shares of stock (giving more ownership to the public) or issue debt (i.e., borrow money). The choice often comes down to which financing method is cheapest. Sometimes, both are too expensive. That’s where convertibles come in.

　　Suppose a start-up company has a stock price of $15 a share and faces a market interest rate of 8%. Suppose that’s 4 percentage points higher than a comparable AAA-rated bond, but remember, the company is a start-up with no proven track record and perhaps no incoming revenue.

　　Issuing more shares in this environment might reduce the value of the equity holders’ shares too much, and if the company were to issue bonds, it would have to pay an interest rate double that of investment-grade securities. Convertibles are the third choice. They pay a lower interest rate, but give their holders an option to convert the bonds into equity if the stock price increases.

　　If the company opted for a convertible issue, it might issue a bond with a face value of $1,000, a coupon of 5%, and convertible to 50 shares of stock. At issuance, the bond pays a rate below the market rate of interest. And because the shares are trading at $15, the converted value of the shares would be $15 x 50 = $750, less than the value of the bond.

　　As the holder of this convertible bond, you would only consider conversion if the shares began trading above $20 ($1,000 ÷ 50 = 20). At that point, it might make more sense to own the shares rather than hold the bond. But that depends on prevailing interest rates (versus the 5% you’re earning) and the opportunity cost of your money. For example, if the company were to start paying a dividend to shareholders, you might want to own the stock so you can capture those dividends.

　　Understanding dilutionAlthough convertible securities solve a funding problem, many existing shareholders dislike them because they cause dilution, that is, a reduction in earnings per share and ownership position. When a convertible bond is exchanged for shares, new shares are created, increasing the total number of shares outstanding. Each of those new shareholders gets a claim on future earnings, as well as the voting power that comes with being a common shareholder.

　　Suppose a company has 1,000 shares outstanding and it issues convertible bonds that eventually require the creation of 500 shares, bringing the total to 1,500.

　　Although existing shareholders still own their original shares, they now represent a smaller percentage of the company’s total equity. If the company earned $500, earnings per share would be 50 cents under the old share count and 33 cents after conversion. But this may still be a better deal for the existing shareholders than issuing straight debt or straight equity, especially because convertible holders won’t exchange their bonds for shares until the stock price is on an upswing.

　　Why use convertibles?In public markets, convertibles are a tool for managing the cost of capital when raising funds. In private markets, they’re used to give venture capitalists bankruptcy protection if the company fails and upside potential if it does well.

　　In bankruptcy, debts must be repaid before any money is distributed to shareholders, which means bondholders, including convertible bond and note holders, have priority. For this reason, many venture investors would rather structure their investment in a start-up as a convertible note rather than as an equity investment. The interest on the note accrues until conversion, so the company doesn’t have to pay interest. If the company does well, then the venture capitalists can convert the note to equity. If it ends up going into bankruptcy, then the venture capitalists have more protection than the equity holders do.

　　The bottom lineConvertible bonds and other convertible securities offer their holders income and the potential for capital appreciation if converting the bond into shares makes sense. They also have seniority over equity in bankruptcy, which makes them flexible for both issuers and buyers.

　　Convertibles function like a bond with a sort of embedded call option, in that you pay a premium (in the form of receiving lower interest payments relative to the market interest rate for comparable debt securities) and you have the potential for extra gains (if the stock appreciates and you convert your bond into equity).

　　Because convertible bonds are considered alternative investments, many institutional investors, including pension plans and university endowments, allocate a portion of their portfolios to them. So, if you’re part of a pension plan, you may be indirectly benefiting from convertible bonds. But if you’re an individual investor looking to add a convertible bond fund to your portfolio, pay close attention to returns compared to those of other bond funds, and keep an eye on the expense ratio. These are complex, professionally managed funds, which means they can be expensive to operate.

　　ReferencesConvertible Securities | investor.gov