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 Vistra, a filing with the SEC revealed that on Wednesday, CFO James A. Burke purchased 30,000 shares of VST, for a cost of $16.60 each, for a total investment of $498,000. Burke was up about 9.0% on the buy at the high point of today's trading session, with VST trading as high as $18.09 at last check today. Vistra is trading up about 1.5% on the day Friday. Before this latest buy, Burke made one other purchase in the past year, buying $310,233 shares for a cost of $18.25 a piece.

And on Thursday, Director Gregory T. Lucier bought $294,750 worth of DENTSPLY SIRONA, buying 5,000 shares at a cost of $58.95 each. This buy marks the first one filed by Lucier in the past twelve months. DENTSPLY SIRONA is trading up about 2.3% on the day Friday. So far Lucier is in the green, up about 4.0% on their purchase based on today's trading high of $61.34.