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.

On Tuesday, Vaxcyte's Director, Patrick J.

Heron, made a $4M buy of PCVX, purchasing 250,000 shares at a cost of $16.00 a piece.

So far Heron is in the green, up about 118.5% on their buy based on today's trading high of $34.96.

Vaxcyte Inc is trading up about 1.7% on the day Wednesday.

This buy marks the first one filed by Heron in the past twelve months.

And at Advance Auto Parts, there was insider buying on Monday, by CEO Thomas Greco who bought 7,285 shares at a cost of $136.13 each, for a total investment of $991,707.

Advance Auto Parts is trading up about 0.7% on the day Wednesday.

So far Greco is in the green, up about 6.8% on their purchase based on today's trading high of $145.45.