Leading analyst Joe Mansueto says investors should know the value of what they’re buying and treat their holding as they would a family business by rarely trading it.”Private company owners rarely buy or sell equity and, when they do, they know the value of their equity. A similar approach works well with public company investing. Also, private company owners think about the worth of their shares at most once or twice a year. You’ll do better with your public company investing if you adopt a similar mindset and don’t obsess with daily fluctuations in value,” he said in an interview to a financial website.