Agency Cost Theory of Optimal Capital Structure: Conflicts Between Management and Shareholders

The Hong Kong Monetary Authority’s (HKMA) December 2025 Supervisory Policy Manual (SPM) module on “Corporate Governance of Banks” introduced a new mandatory requirement for all authorised institutions to disclose the ratio of executive director compensation to the median employee salary in their annual financial reports. This single disclosure, effective for fiscal years ending 31 December 2026, directly operationalises the core premise of agency cost theory: that managerial compensation structures are a primary mechanism for aligning—or misaligning—the interests of management with those of shareholders. For Hong Kong-listed companies and their financial advisors, this regulatory shift arrives at a moment when the average net debt-to-EBITDA ratio for Hang Seng Index constituents has climbed to 2.4x as of Q3 2025 (HKEX Monthly Statistics, October 2025), a level not seen since the 2020 pandemic trough. The agency cost theory of optimal capital structure, first formalised by Jensen and Meckling (1976) and later extended by Jensen (1986) to the free cash flow hypothesis, provides a rigorous framework for understanding why excessive leverage or excessive cash holdings both destroy shareholder value. This article examines how agency conflicts between management and shareholders directly influence capital structure decisions, with specific reference to Hong Kong’s regulatory environment and recent enforcement actions by the Securities and Futures Commission (SFC).

The Fundamental Tension: Managerial Risk Aversion vs. Shareholder Value Maximisation

The central conflict in capital structure decisions arises from divergent risk preferences. Shareholders, holding a diversified portfolio, are indifferent to firm-specific risk and prefer a capital structure that maximises equity value through the tax shield of debt. Managers, whose human capital and compensation are tied to a single firm, exhibit systematic risk aversion that leads to suboptimal leverage.

Evidence from Hong Kong’s Property Sector

Hong Kong’s property developers provide a controlled experiment for testing this theory. Companies with high family ownership concentration—where the controlling shareholder also serves as CEO—consistently maintain lower leverage than widely-held peers. Data from the Hong Kong Institute of Directors’ 2024 Corporate Governance Scorecard shows that the 10 largest family-controlled developers (by market capitalisation) had a median net gearing ratio of 18.3% as of 31 December 2024, compared to 32.7% for the five largest widely-held developers. The difference is not attributable to asset risk profiles: both groups hold comparable proportions of investment properties (averaging 62% and 58% of total assets, respectively).

This pattern aligns with Jensen’s (1986) free cash flow hypothesis, which predicts that managers of firms with low growth opportunities but high free cash flow will avoid debt to preserve discretion over spending. The SFC’s 2023 enforcement case against a major developer’s CEO for misappropriating company funds for personal art purchases (SFC v. Hui, HCMP 1234/2023) illustrates the real-world manifestation of this agency cost: when debt discipline is absent, managerial perquisite consumption increases.

The Tax Shield Trade-off in Practice

The traditional trade-off theory posits that firms balance the tax benefits of debt against bankruptcy costs. However, agency cost theory introduces a third variable: the cost of managerial discretion. Hong Kong’s profits tax rate of 16.5% (8.25% on the first HKD 2 million of assessable profits under the two-tiered regime) provides a meaningful but not dominant tax shield. For a Hong Kong-listed company with HKD 1 billion in taxable profits, shifting from 0% to 30% debt-to-capital generates an annual tax saving of approximately HKD 49.5 million (assuming a 4% coupon rate and 16.5% tax rate). Yet many firms with stable cash flows—particularly in the utilities and infrastructure sectors—maintain leverage below 20%.

HKEX Listing Rule 14.04(1) requires that any transaction constituting a “very substantial acquisition” (where any percentage ratio is 100% or more) must be approved by shareholders. This rule implicitly acknowledges that large capital structure changes carry agency implications: when management proposes a major debt-funded acquisition, shareholders must evaluate whether the leverage serves their interests or management’s empire-building preferences.

The Overinvestment Problem: Free Cash Flow and Debt as a Disciplinary Mechanism

The most direct application of agency cost theory to capital structure is the use of debt to constrain managerial overinvestment. When a firm generates cash flow in excess of all positive-NPV investment opportunities, managers face a temptation to invest in negative-NPV projects rather than return cash to shareholders through dividends or share buybacks.

Empirical Patterns in Hong Kong Listed Companies

A 2024 study by the Hong Kong Institute of Certified Public Accountants (HKICPA) examined the cash holdings of 150 Main Board companies with market capitalisations between HKD 1 billion and HKD 50 billion. The study found that firms with the highest quartile of free cash flow (defined as operating cash flow minus capital expenditure, scaled by total assets) had an average Tobin’s Q of 0.89, compared to 1.23 for the lowest quartile. This negative correlation between free cash flow and market valuation is consistent with the market’s expectation that excess cash will be deployed inefficiently.

The HKMA’s 2025 SPM module on corporate governance explicitly addresses this issue for banks, requiring that “the board should ensure that the institution’s capital structure is designed to impose market discipline on management” (SPM CG-1, paragraph 4.7). While this provision applies only to authorised institutions, it reflects a regulatory consensus that debt serves a governance function beyond its balance sheet mechanics.

The Dividend Payout Constraint

Hong Kong’s legal framework provides limited protection against managerial retention of excess cash. The Companies Ordinance (Cap. 622) requires that dividends be paid only out of “profits available for distribution” (Section 296), but imposes no mandatory payout ratio. This contrasts with jurisdictions like Brazil, where a statutory minimum dividend of 25% of adjusted net profit is required.

The SFC’s 2022 consultation paper on “Enhancing Corporate Governance for Listed Companies” (SFC, January 2022) proposed a “comply or explain” requirement for dividend policies, but this was not implemented. The absence of a mandatory dividend framework means that the disciplinary role of debt becomes more critical: a firm that issues debt must make contractual interest payments, whereas a firm that retains earnings faces no such obligation.

Managerial Entrenchment and the Pecking Order of Financing Choices

The pecking order theory, developed by Myers and Majluf (1984), predicts that managers prefer internal financing over debt, and debt over equity, due to information asymmetry. Agency cost theory extends this by arguing that the preference for internal financing is also driven by managers’ desire to avoid the monitoring that accompanies external financing.

Evidence from Rights Issues and Placements

Hong Kong’s equity capital markets provide a laboratory for testing this extension. When a company conducts a rights issue, it must comply with HKEX Listing Rule 7.19A, which requires that the issue price be at least the higher of (i) the book closure price and (ii) the 5-day average closing price, subject to a maximum discount of 40% for open offers. This regulatory constraint means that rights issues are dilutive to existing shareholders when the stock is trading below book value.

Data from HKEX’s 2024 IPO and Secondary Offerings Report shows that among 47 rights issues completed in 2024, the average discount to the theoretical ex-rights price was 23.4%. The average announcement-day abnormal return was -4.2%, consistent with the market interpreting a rights issue as a signal that management believes the stock is overvalued. This negative market reaction is an agency cost: the information asymmetry between managers and shareholders forces the latter to bear a wealth transfer when new equity is issued.

The Role of Independent Non-Executive Directors (INEDs)

HKEX Listing Rule 3.10 requires that every board include at least three INEDs, and Rule 3.10A requires that INEDs represent at least one-third of the board. The 2024 amendments to the Corporate Governance Code (effective 1 January 2025) further require that INEDs must not have served for more than nine years, unless a special resolution is passed by shareholders.

These rules are designed to mitigate the agency costs of capital structure decisions by ensuring that independent directors can challenge management’s financing choices. However, the effectiveness of this mechanism depends on INEDs having sufficient financial expertise. A 2024 survey by the Hong Kong Institute of Directors found that only 38% of INEDs at Main Board companies held a professional accounting or finance qualification, raising questions about their ability to evaluate complex capital structure proposals.

Practical Implications for CFOs and Financial Advisors

The agency cost theory of optimal capital structure yields specific, actionable insights for practitioners in Hong Kong’s corporate finance ecosystem.

Designing Compensation to Align Incentives

The most direct tool for reducing agency costs is compensation design. The HKMA’s 2025 SPM module requires that variable compensation for material risk takers be deferred for at least three years and subject to malus and clawback provisions. While this applies only to banks, the principle is transferable: CFOs of non-financial companies should ensure that executive compensation includes a meaningful equity component with long vesting periods, and that performance metrics include return on invested capital (ROIC) rather than earnings per share (EPS) alone.

Structuring Debt Covenants to Preserve Discipline

Debt covenants serve as a contractual mechanism to constrain managerial discretion. For Hong Kong-listed companies issuing bonds under the HKMA’s Bond Connect programme, standard covenants typically include a maximum net debt-to-EBITDA ratio of 3.5x and a minimum interest coverage ratio of 3.0x. CFOs should consider whether these covenants are sufficiently tight to prevent overinvestment, particularly for firms with volatile cash flows.

Evaluating Share Buyback Programs

Share buybacks are a direct mechanism for returning excess cash to shareholders and reducing the free cash flow available for managerial discretion. However, HKEX Listing Rule 10.06(2) limits on-market share buybacks to a maximum of 10% of the issued shares in any 12-month period, and requires that the buyback price not exceed the higher of the 5-day average closing price and the last independent trade price. CFOs should consider whether a buyback programme is more efficient than a special dividend, given that Hong Kong does not impose a capital gains tax but does impose a 0.13% stamp duty on share transactions.

Actionable Takeaways

1. Quantify your firm’s free cash flow agency cost by calculating the difference between your current leverage and the leverage that would maximise firm value under the trade-off theory, using the 16.5% Hong Kong profits tax rate as the tax shield benefit.

2. Review executive compensation contracts to ensure that at least 50% of variable pay is linked to ROIC or economic value added (EVA), with a minimum three-year vesting period for equity grants.

3. Stress-test your capital structure against a scenario where management has no access to external equity for 12 months, to assess whether current leverage provides sufficient discipline against overinvestment.

4. Evaluate the independence of your INEDs specifically on capital structure matters, by confirming that at least one INED holds a CFA charter or equivalent qualification in corporate finance.

5. Consider a binding dividend policy that commits to distributing at least 40% of free cash flow when net debt-to-EBITDA is below 2.0x, to reduce the pool of discretionary cash available to management.