The vast majority of my investing is in retirement accounts and won't be tapped for income until I reach at least 59.5 years old. However, I have a very small taxable investing portfolio (less than $5k) with Ally Invest where I invest in a handful of stocks that I value. I do not use the earnings as income – I simply hold these stocks. But I have an unrealized gain of $340 from this year so far.
Residual income is calculated as net income less a charge for the cost of capital. The charge is known as the equity charge and is calculated as the value of equity capital multiplied by the cost of equity or the required rate of return on equity. Given the opportunity cost of equity, a company can have positive net income but negative residual income.