As the saying goes, there are many possible reasons for an insider to sell a stock, but only one reason to buy -- they expect to make money. So let's look at two noteworthy recent insider buys.

At PennyMac Financial Services, a filing with the SEC revealed that on Tuesday, Director Farhad Nanji purchased 298,655 shares of PFSI, at a cost of $57.93 each, for a total investment of $17.30M. PennyMac Financial Services is trading up about 4.4% on the day Thursday. Before this latest buy, Nanji bought PFSI at 7 other times during the past twelve months, for a total cost of $94.31M at an average of $62.51 per share.

And on Monday, John J. Mack purchased $957,120 worth of New Fortress Energy, purchasing 24,000 shares at a cost of $39.88 each. Before this latest buy, Mack made one other purchase in the past year, buying $948,783 shares for a cost of $25.13 a piece. New Fortress Energy is trading up about 8.9% on the day Thursday.