(1) It is generally better to issue
safe securities than risky ones.
Firms should go to
bond markets for external capital,
but raise equity by retention if possible.
That is, external financing using debt is better than financing by equity.
(2) Firms whose investment opportunities outstrip operating cash flows, and which have used up their ability to issue low-risk debt, may forego good investments rather than issue risky securities to finance them.
This is done in the existing stockholders’ interest. However, stockholders are better off ex ante - i.e., on average - when the firm carries sufficient financial slack to undertake good investment opportunities as they arise.