The accounting identity states that the book value of a company's assets (A) equals its liabilities (L) plus owners equity (OE), so A = L + OE.
The finance version states that the market value of a company's assets (V) equals the market value of its debt (D) plus equity (E), so V = D + E.
Therefore a business's assets can be seen as a portfolio of the debt and equity that fund the assets.
Let ##\sigma_\text{V total}^2## be the total variance of returns on assets, ##\sigma_\text{V syst}^2## be the systematic variance of returns on assets, and ##\sigma_\text{V idio}^2## be the idiosyncratic variance of returns on assets, and ##\rho_\text{D idio, E idio}## be the correlation between the idiosyncratic returns on debt and equity.
Which of the following equations is NOT correct?