Insiders often buy when stocks go on sale, and that is what we see happening at Penn West Petroleum Ltd. The stock dropped earlier this month after third quarter results failed to meet expectations of some investors. A few days after the news, the company made sweeping changes in the executive suite. While investors were selling in the market, six Penn West Petroleum insiders spent a combined total of $1.5-million buying stock. The biggest purchaser was board chair John Brussa who added 83,400 shares to his holdings.