Equity financing, often referred to as shareholders' equity or net worth, consists of the capital contributed by shareholders plus the retained earnings (reserves and surplus) accumulated by the company over time. This represents the total claim of the equity holders on the assets of the business.

The Modigliani-Miller approach relies on arbitrage (a-4). The Net Operating Income approach is a theory of capital structure (b-3). Commercial papers are short-term money market instruments (c-1). Factoring is a method of managing working capital (d-2).

The Net Operating Income (NOI) approach suggests that the market values the firm based on its net operating income and the overall capitalization rate. According to this theory, the weighted average cost of capital remains constant as leverage increases, because the increase in the cost of equity exactly offsets the benefit of using cheaper debt, leaving the total value of the firm unchanged.

Debt financing offers several benefits: interest payments are tax-deductible, which lowers the effective cost of debt. It often reduces the Weighted Average Cost of Capital (WACC) due to the tax shield, and unlike equity financing, it allows the existing owners to retain full control of the company without issuing new voting shares.

Capital structure theories focus on how a firm finances its operations through debt and equity. The Net Income approach, Net Operating Income approach, and the Modigliani-Miller approach are all well-established theories in financial management. The 'Gross Profit approach' is not a recognized theory for determining capital structure; it is a measure of operational profitability rather than financing strategy.

As a company increases its financial leverage, the risk profile for equity shareholders rises due to the fixed obligation of debt servicing. To compensate for this increased financial risk, shareholders demand a higher rate of return on their investment, which is an implicit cost of debt financing.

The Net Income (NI) approach suggests that a firm can increase its total value and reduce its overall weighted average cost of capital (WACC) by increasing the proportion of debt in its capital structure. This is because debt is generally cheaper than equity, and the NI approach assumes that the cost of debt and equity remain constant regardless of the leverage level.

The Net Income approach posits that because debt is a cheaper source of financing than equity, increasing the debt component in the capital structure will continuously reduce the overall weighted average cost of capital. Consequently, the firm's value increases as the debt ratio increases, suggesting that a highly levered capital structure is theoretically optimal.

Stock repurchase is primarily viewed as a financing decision because it involves altering the company's capital structure by reducing equity. It is distinct from an investment decision, which typically involves the allocation of capital toward productive assets or projects intended to generate future cash flows for the firm's operations.

Trading on equity is a double-edged sword. While it can increase returns for shareholders when the return on assets exceeds the cost of debt, it also increases financial risk. If the return on assets falls below the interest rate, it can lead to financial distress, meaning it is only 'potentially' beneficial depending on market conditions.