Debtholders prefer different projects from shareholders. In the following scenario, which group will support which project?
Project A has a guaranteed payoff of $200 million, which will exactly compensate the debtholders of the firm. Project B has a 50% probability of a $400 million payoff and a 50% probability of a zero payoff. Debtholders would support one of these projects and not the other. Shareholders would support one of these projects over the other.
In this case, debtholders would support Project A while shareholders would support Project B.
Project A is risk-free. It will certainly pay off the debtholders. Therefore, they will support it. This is particularly true because in Project B, they have a 50% chance of getting nothing and a 50% chance of getting paid back. In Project A, they have a 100% chance of getting paid. If Project B succeeds, they don't get any more money than they would in Project A. So why gamble?
But Project A does shareholders no good. The income will only be enough to pay the debtholders with nothing left to pay out in dividends. So, in Project A, shareholders have a 100% chance of getting nothing. At least in Project B they have a 50% chance of splitting $200 million (what's left after the debts are paid) between them.