Myers–Majluf Adverse-Selection Financing Model

The Myers–Majluf adverse-selection financing model is a foundational theory of corporate financing in business and economics theory that explains why firms issue securities in a particular order and why information gaps can cause good investments to be abandoned. Published by Stewart Myers and Nicholas Majluf in the 1984 Journal of Financial Economics article "Corporate Financing and Investment Decisions When Firms Have Information That Investors Do Not Have", it applies the logic of adverse selection to the equity issuance decision. Managers who act in the interest of existing shareholders will avoid selling undervalued shares to new investors, and investors anticipate this behavior. The result is a systematic discount on new equity and a financing hierarchy known as the pecking order.

The model contains a firm with assets in place and a growth opportunity that requires an investment outlay I. The firm holds financial slack S < I in cash or marketable securities, so it must raise at least E = I − S from outside investors. Managers observe the true values of both assets in place, a, and the growth option, b, while outside investors know only the probability distribution of the pair (a, b). This is a textbook case of information asymmetry between insiders and outsiders.

Two assumptions drive the results. First, the manager acts in the interest of old shareholders, those holding claims at the moment before issuance, and not the new investors. Second, the capital market is otherwise perfect: no taxes, no transaction costs, and risk-neutral investors, which echoes the conditions of the Modigliani–Miller theorem. The only friction is the information gap.

Suppose the firm issues equity to raise E. New investors pay a price P per share based on their expectation of firm value conditional on the decision to issue and invest. Old shareholders obtain the value of the firm net of the stake handed to the new shareholders. If the firm issues and invests, total value is a + b + S − I + I = a + b + S, shared between old and new holders in proportion to the new share fraction E / P′, where P′ is the post-announcement firm value.

The managers' decision rule follows from comparing old shareholders' payoffs:

• If the firm does not issue, old shareholders receive a + S.
• If the firm issues and invests, old shareholders receive a fraction of a + b + S determined by the issue price P, which reflects the market's average assessment.

When the true value a is above the market's pooled estimate, issuing means selling shares for less than they are worth, transferring wealth from old to new shareholders. Investment is attractive only if the net present value b of the growth option exceeds the wealth transfer. A firm that is sufficiently overvalued gains from the issue, while an undervalued firm may decline to issue even though b > 0.

The equilibrium is a pooling or partially separating one in which only firms with a below a threshold issue equity. Because the manager's willingness to issue signals that the stock is not undervalued, a rational market lowers its estimate when the issue is announced and the share price falls, which is the same mechanism Akerlof (1970) described for used cars.

The key welfare implication is underinvestment. A firm with a positive-NPV project and high-quality assets in place may skip the investment because issuing equity at the discounted price would give new shareholders too much of the existing assets' value. The loss is a deadweight cost, so the outcome violates Pareto efficiency. The model does not require managers to be irrational or self-serving; it follows from loyalty to existing shareholders in the presence of asymmetric information.

Financial slack mitigates the problem. If the firm holds enough cash or has enough debt capacity to fund I without issuing equity, it can invest in every positive-NPV project at no cost. Slack therefore has option value, which explains why firms may hold substantial liquid assets and keep spare borrowing capacity. The point sits in tension with free-cash-flow theories in which slack encourages wasteful spending, a trade-off discussed in the Jensen–Meckling agency cost theory.

Extending the argument to different securities yields a hierarchy. Securities whose payoffs are less sensitive to the firm's private information are less underpriced:

1. Internal funds: retained earnings carry no adverse-selection discount.
2. Safe debt: its value depends little on private information about a and b, so the mispricing is small.
3. Risky debt and convertible securities: mispricing grows as default risk rises.
4. Equity: most sensitive to private information, hence the largest discount.

Myers (1984), in "The Capital Structure Puzzle", summarized these implications as the pecking order theory. Contrary to the trade-off theory, there is no optimal debt ratio; leverage reflects the cumulative history of financing deficits and the firm's profitability. Profitable firms accumulate internal funds and borrow little, while firms with large investment needs borrow more.

Shyam-Sunder and Myers (1999) regressed net debt issuance on the financing deficit for a sample of large US firms, finding a coefficient close to one, which they interpreted as support for the pecking order. Frank and Goyal (2003) used a broader sample that included small firms and found the opposite: net equity issues track the deficit more closely than net debt issues for small, high-growth firms, which indicates that the pecking order fails where information asymmetry is greatest. Other findings include:

• Announcements of seasoned equity offerings are followed by average abnormal returns near −2% to −3%, consistent with the discount mechanism.
• Debt issuance announcements show small or zero reactions.
• Negative leverage–profitability correlations are consistent with the hierarchy but can also be explained by other theories.

These mixed results suggest that the pecking order describes some firms' behavior, particularly mature firms with moderate information problems, but is not a universal law.

Later work enriched the model. Signaling approaches, such as those drawing on signaling logic, show that firms may use debt or dividends to convey quality. Models with moral hazard on the manager's side add incentive conflicts, so the optimal financing mix balances adverse selection against agency costs. Fazzari, Hubbard, and Petersen's investment–cash-flow sensitivity literature draws on the same logic of costly external finance. A limitation is the model's static two-period structure, which neglects dynamic issuance timing and market-timing behavior in which managers issue equity when valuations are high.

1. Myers, S. C., & Majluf, N. S. (1984). Corporate Financing and Investment Decisions When Firms Have Information That Investors Do Not Have. Journal of Financial Economics, 13(2), 187–221. https://doi.org/10.1016/0304-405X(84)90023-090023-0)
2. Myers, S. C. (1984). The Capital Structure Puzzle. The Journal of Finance, 39(3), 574–592. https://doi.org/10.1111/j.1540-6261.1984.tb03646.x
3. Shyam-Sunder, L., & Myers, S. C. (1999). Testing Static Tradeoff against Pecking Order Models of Capital Structure. Journal of Financial Economics, 51(2), 219–244. https://doi.org/10.1016/S0304-405X(98)00051-800051-8)
4. Frank, M. Z., & Goyal, V. K. (2003). Testing the Pecking Order Theory of Capital Structure. Journal of Financial Economics, 67(2), 217–248. https://doi.org/10.1016/S0304-405X(02)00252-000252-0)
5. Akerlof, G. A. (1970). The Market for "Lemons": Quality Uncertainty and the Market Mechanism. The Quarterly Journal of Economics, 84(3), 488–500. https://doi.org/10.2307/1879431