Diversify safely but DIVERSITY. You do not need to get the best and highest return all the time. If so, you are not earning passive income you are earning active income which is taxed differently (see IRS.GOV passive -vs- active income definitions). As an investor you do not need to be chasing ‘the almighty dollar’. This is a losing proposition. Make the dollar come to you.
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.