# Fight Finance

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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?