A corporate bond is issued by a company to raise money directly from investors rather than through a bank loan. The bondholder is a creditor, not a co-owner: they take no share of profit and cast no vote at the shareholders' meeting, but their claims rank ahead of shareholders' if the issuer runs into difficulty.
The yield on a corporate issue is the yield on government paper of the same maturity plus a credit spread — the premium for that particular issuer's risk. The weaker the credit quality, the wider the spread. The market is conventionally split into tiers: the first holds the largest companies with high ratings, the second sound but less prominent names, and the third the high-yield segment, where an elevated rate corresponds directly to an elevated chance of trouble.
Some corporate issues carry a put option — a date on which the holder may present the bond for early redemption at par. The issuer typically gains the right to reset the coupon for the following period in exchange. For the investor this means the real horizon ends at the put date rather than at the formal maturity, and yield is calculated to the put accordingly.
Subordinated issues, most often from banks, are a category of their own. In a resolution or bankruptcy their claims rank behind those of all other creditors, and in certain cases the debt can be written off in full. The higher yield on such bonds is payment for exactly that condition.
