When a number of billionaire investors are all buying the same stock in the same quarter, that can be a bullish indicator for the company.It's understandable why retail investors might see a hedge fund making a big new investment in a company and get excited about that stock. After all, billionaire hedge fund managers are generally viewed as the best stock pickers on Wall Street, and some of them even have the track records of investment returns to back that premise up.But retail investors must remember tha ...