Insider buying can be an encouraging signal for potential investors.A couple of companies saw insiders returning to the buy window last week.One director bought shares of two of this companies in the past week. Conventional wisdom says that insiders and 10 percent owners really only buy shares of a company for one reason -- they believe the stock price will rise and they want to profit from it. So insider buying can be an encouraging signal for potential investors, particularly with markets at all-time highs.Source