Theory
The pecking order theory is from Myers (1984) and Myers and Majluf (1984).
Since it is well known, we can be brief. Suppose that there are three sources of
funding available to firms: retained earnings, debt, and equity. Retained earnings
have no adverse selection problem. Equity is subject to serious adverse selection
problems while debt has only a minor adverse selection problem. From the point of
view of an outside investor, equity is strictly riskier than debt. Both have an adverse
selection riskpremium, but that premium is large on equity. Therefore, an outside
investor will demand a higher rate of return on equity than on debt. From the
perspective of those inside the firm, retained earnings are a better source of funds
than is debt, and debt is a better deal than equity financing. Accordingly, the firm
will fund all projects using retained earnings if possible. If there is an inadequate
amount of retained earnings, then debt financing will be used. Thus, for a firm in
normal operations, equity will not be used and the financing deficit will match the net
debt issues.
In reality, company operations and the associated accounting structures are more
complex than the standard pecking order representation. This implies that in order
to test the pecking order, some form of aggregation must be used.