What happened

Shares of Exact Sciences (NASDAQ:EXAS), a diagnostics company focused on cancer, fell 11.7% in December, according to data from S&P Global Market Intelligence. While it was a light month on the news front, SEC filings did reveal that a few key insiders lightened up on their stock holdings during the month. It is possible that the selling convinced a few traders to follow suit. 

So what

SEC filings showed that CEO Kevin Conroy unloaded more than 100,000 shares on two separate occasions during the month. Those sales netted him about $13 million in total.

Chief science officer Graham Lidgard also decided to take advantage of the company's surging share price and sold about $2.4 million worth of stock.

With little other news to go on, it is possible that this insider selling caused a few traders to head for the exits. 

Another possibility is this high-flying growth stock simply decided to take a breather for no reason at all.

Man holding bull and bear with bull in focus

Image source: Getty Images.

Now what

Should investors be worried about this insider selling? I don't think so. The reason is that even after this round of selling, CEO Conroy still holds 1.5 million shares of common stock and options. He also has another 1.1 million shares and options that could become vested over time.

CSO Lidgard is in a similar position. His stock sales only represent a fraction of his total ownership, so he still remains heavily incentivized.

It is common for insiders to sell, so rather than fret over what they are doing, Exact Sciences' bulls should remain heads-down focused on its long-term potential. On that front, there are still plenty of reasons to remain optimistic about this company's future, so I see no reason for bulls to abandon ship.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.