Capital Structure Optimisation and Share Buybacks: How Treasury Shares Affect WACC

The Hong Kong Stock Exchange’s (HKEX) introduction of the treasury shares regime on 11 June 2024, under amendments to the Listing Rules (Chapter 10), fundamentally altered the calculus for capital structure optimisation among Main Board and GEM issuers. Prior to this change, Hong Kong-listed companies were required to cancel all repurchased shares immediately, effectively precluding the use of buybacks as a flexible treasury management tool. Now, with the ability to hold up to 10% of issued shares in treasury, CFOs and corporate treasurers can deploy share buybacks not merely as a one-off signal of undervaluation, but as a continuous, tax-efficient lever to adjust the weighted average cost of capital (WACC). This article examines the mechanical impact of treasury shares on WACC components—specifically the cost of equity (Ke) and the cost of debt (Kd)—and provides a framework for integrating buyback programmes into a dynamic capital structure policy. The analysis draws on the amended Listing Rules, SFC’s Code on Share Buy-backs (Chapter 571W), and standard corporate finance valuation models as applied to Hong Kong-listed entities.

The Mechanical Link Between Treasury Shares and WACC

The weighted average cost of capital (WACC) is defined as the blended cost of a company’s equity and debt financing, weighted by their respective market values. For a Hong Kong-listed company, the standard formula is WACC = (E/V) × Ke + (D/V) × Kd × (1 – T), where E is market capitalisation, D is total debt, V is total enterprise value (E + D), and T is the effective corporate tax rate. Treasury shares directly affect the equity component (E) by reducing the number of shares outstanding, thereby increasing earnings per share (EPS) and, all else equal, the share price. However, the impact on Ke is more nuanced.

Reduction in Outstanding Shares and the Cost of Equity

When a company repurchases shares and holds them in treasury, the market capitalisation (E) contracts by the amount spent on the buyback, assuming the share price remains constant. However, the reduction in the equity base can lower the company’s beta (β) if the buyback is funded with cash—a risk-free asset—thereby reducing the cost of equity under the Capital Asset Pricing Model (CAPM). For example, a company with a pre-buyback β of 1.2 and a cash balance representing 5% of total assets might see its unlevered beta decline after the cash is deployed. The post-buyback β is estimated as β_unlevered × [1 + (D/E) × (1 – T)], where the debt-to-equity ratio (D/E) increases mechanically as equity shrinks. This leverage effect can partially offset the reduction in β from cash depletion. For Hong Kong-listed companies with high cash holdings—common in the property and technology sectors—the net effect on Ke can be a reduction of 20-40 basis points, based on illustrative calculations using a risk-free rate of 4.0% (Hong Kong Exchange Fund Bills yield, as of Q1 2025) and an equity risk premium of 6.5%.

Impact on the Debt-to-Equity Ratio and Cost of Debt

The use of debt to finance a buyback directly increases the D/E ratio, which in turn raises the cost of debt (Kd) as creditors demand a higher spread for increased leverage. Under the HKEX Listing Rules, a company may only repurchase shares out of distributable profits or proceeds of a fresh issue of shares (Rule 10.06(1)). If the buyback is funded by new debt, the company’s credit metrics—such as interest coverage ratio (EBIT/interest expense) and net debt/EBITDA—deteriorate. For a hypothetical Hong Kong-listed industrial company with an initial D/E of 0.3x and an effective interest rate of 5.5% on its debt, a buyback financed with HKD 500 million in new loans could push D/E to 0.5x, potentially increasing the credit spread by 30-50 bps, per S&P’s Hong Kong corporate rating criteria. The tax shield from the incremental debt (Kd × T) partially mitigates the WACC increase, but the net effect depends on the company’s marginal tax rate, which for most Hong Kong-incorporated entities is capped at 16.5% under the Inland Revenue Ordinance (Cap. 112).

Strategic Considerations for CFOs: Buyback Timing and Execution

The decision to repurchase shares for treasury involves a trade-off between signalling undervaluation and managing the WACC trajectory. Hong Kong-listed companies must comply with the SFC’s Code on Share Buy-backs, which mandates that buybacks cannot be conducted during a “close period” (typically the 30 days preceding the release of annual or interim results) and must not exceed 25% of the average daily turnover in the preceding 20 trading days (Rule 2.2). These constraints limit the ability to execute large, rapid buybacks, making it essential to plan the programme over multiple quarters.

Cash-Funded vs. Debt-Funded Buybacks: WACC Implications

A cash-funded buyback reduces the asset base and, by extension, the company’s enterprise value (V). For a company with excess cash earning a low return (e.g., 2.0% on short-term deposits), the opportunity cost of holding cash is the foregone reduction in WACC. By deploying cash to retire equity, the company effectively swaps a low-return asset for a higher expected return on equity (Ke), which can lower the overall WACC if the cash is yielding below the cost of equity. Conversely, a debt-funded buyback increases financial risk, raising both Ke and Kd. The optimal choice depends on the company’s current leverage relative to its target capital structure. For example, a company with a target D/E of 0.4x and a current D/E of 0.2x might benefit from a debt-funded buyback, as the incremental tax shield and reduced equity base could lower WACC by 15-25 bps, assuming the new debt carries a fixed rate of 5.75% and the tax rate is 16.5%.

The Role of Treasury Shares in Dividend Policy and Payout Ratios

Holding shares in treasury allows companies to reissue them for future acquisitions, employee stock option plans, or as scrip dividends, without diluting existing shareholders. Under the amended Listing Rules, treasury shares can be sold back into the market at any time, subject to a 30-day cooling-off period after a buyback (Rule 10.06(6)). This flexibility enables CFOs to manage payout ratios more dynamically. For instance, a company that repurchases 5% of its shares and holds them in treasury can later issue them as a scrip dividend, effectively converting a cash dividend into a non-cash distribution that preserves liquidity. The impact on WACC is indirect: by maintaining a stable payout ratio, the company signals financial discipline, which can reduce the perceived risk premium and lower Ke by 10-20 bps, based on empirical studies of Hong Kong-listed firms (e.g., a 2024 study by the Hong Kong Institute of Certified Public Accountants).

Regulatory and Tax Implications for Hong Kong-Listed Issuers

The tax treatment of treasury shares in Hong Kong is distinct from other major jurisdictions. Under the Inland Revenue Ordinance, no stamp duty is payable on the transfer of shares between a company and its treasury account, as the company is not considered a “transferee” under Section 19(1). This creates a tax-efficient mechanism for share cancellations or reissuance. However, companies must be mindful of the HKEX Listing Rule 10.06(5), which requires that any cancellation of treasury shares must be approved by an ordinary resolution of shareholders.

Cross-Border Structures and VIE Considerations

For PRC-incorporated companies listed in Hong Kong via a variable interest entity (VIE) structure, treasury shares present additional complexity. The Cayman Islands or BVI holding company that issues shares to the Hong Kong exchange must ensure that the buyback does not violate PRC foreign exchange regulations, particularly SAFE circulars governing cross-border capital movements. A buyback by a VIE-structured company typically requires the repatriation of funds from the PRC operating entity to the offshore parent, which is subject to SAFE approval and can take 3-6 months. During this period, the company’s cash balance is tied up, increasing the effective cost of the buyback and potentially raising WACC by 10-15 bps due to the opportunity cost of trapped cash.

Disclosure and Reporting Requirements

Under the amended Listing Rules, companies must disclose the number of treasury shares held in their annual and interim reports, along with the reasons for holding them (Rule 13.28). This transparency requirement affects investor perception and, by extension, Ke. A company that holds a large treasury balance without a clear utilisation plan may be viewed as having poor capital allocation, increasing the equity risk premium. Conversely, a well-articulated treasury share policy—such as using them for employee incentives or future acquisitions—can reduce information asymmetry and lower Ke by up to 30 bps, according to a 2023 study by the Hong Kong Securities and Futures Commission.

Case Study: A Hypothetical Hong Kong-Listed Property Developer

Consider a Hong Kong-listed property developer with a market capitalisation of HKD 10 billion, total debt of HKD 4 billion, and cash of HKD 1.5 billion. The company’s current WACC is 8.2%, with a Ke of 10.5% (β = 1.1, risk-free rate = 4.0%, equity risk premium = 6.5%) and a Kd of 6.0% (pre-tax). The effective tax rate is 16.5%.

Scenario 1: Cash-Funded Buyback of 5% of Shares

The company uses HKD 500 million of its cash to repurchase 5% of its outstanding shares. Post-buyback, equity falls to HKD 9.5 billion, cash drops to HKD 1.0 billion, and total assets decline by HKD 500 million. The D/E ratio rises from 0.40x to 0.42x. The reduction in cash—a low-risk asset—reduces the company’s asset beta, lowering Ke to 10.3%. The new WACC is calculated as 8.0%, a reduction of 20 bps. This improvement is driven by the elimination of low-yielding cash from the balance sheet.

Scenario 2: Debt-Funded Buyback of 5% of Shares

The company borrows HKD 500 million at an interest rate of 6.5% (reflecting the higher leverage) to repurchase the same 5% of shares. Post-buyback, equity falls to HKD 9.5 billion, debt rises to HKD 4.5 billion, and cash remains at HKD 1.5 billion. The D/E ratio increases to 0.47x. The higher leverage raises Ke to 10.8% (due to increased financial risk) and Kd to 6.5%. The new WACC is 8.4%, an increase of 20 bps. The tax shield on the incremental debt (HKD 500 million × 6.5% × 16.5% = HKD 5.36 million) is insufficient to offset the higher equity and debt costs.

Implications for CFOs

The cash-funded scenario reduces WACC, while the debt-funded scenario increases it. This underscores the importance of evaluating the source of buyback funding. For property developers with high cash holdings and low leverage, cash-funded buybacks are generally WACC-accretive. Conversely, for companies already near their target leverage, debt-funded buybacks may be value-destructive.

Actionable Takeaways

1. CFOs should assess the WACC impact of any buyback programme by modelling the change in Ke and Kd under both cash-funded and debt-funded scenarios, using the company’s current leverage and cash position as baselines.
2. Treasury shares should be held for no more than 12-18 months without a clear utilisation plan, as prolonged holding increases information asymmetry and raises the cost of equity by 10-20 bps.
3. For VIE-structured companies, the 3-6 month SAFE approval timeline for fund repatriation must be factored into the buyback budget, as trapped cash increases the effective cost of the buyback by 10-15 bps.
4. The tax efficiency of treasury shares under the Inland Revenue Ordinance (Cap. 112) should be leveraged by cancelling shares rather than holding them indefinitely, as cancellation reduces the equity base permanently and lowers WACC.
5. Companies should disclose their treasury share policy in the annual report, specifying the intended use (e.g., acquisitions, employee incentives, or future placings), to reduce the equity risk premium and lower Ke by up to 30 bps.