When debt to equity ratio rises why does the asset beta not change?

The asset beta reflects the risk of the firm's underlying assets, independent of its capital structure. When the debt-to-equity ratio rises, the firm's financial leverage increases, which may affect the equity beta but not the asset beta itself. The asset beta remains constant because it is based on the business's operational risk and market conditions, rather than the financing mix. Therefore, while the equity beta adjusts to reflect the higher financial risk, the asset beta remains unchanged.