What happened

Shares of BJ's Restaurants (NASDAQ:BJRI) jumped nearly 10% on Friday following share purchases by the company's chief executive officer and a board director.

So what

On Aug. 15, CEO Greg Trojan bought 14,400 shares of BJ's Restaurants stock at an average price of $32.92. Following the transaction, Trojan owned a total of 59,388 shares of the company's common stock, which is currently valued at more than $2.1 million. 

A person pressing a button labeled Buy.

Image source: Getty images.

Notably, board member Gerald Deitchle also purchased BJ's Restaurants stock that same day. Deitchle bought 3,000 shares at an average price of $33.81. Deitchle reported ownership of a total of 27,095 shares of common and restricted stock, valued at nearly $1 million. 

Now what

Executives can sell for many reasons, such as converting stock-based compensation into cash and diversifying their investment portfolios. Yet it's often said that insiders typically buy for one main reason: They think the stock's price is going to rise.

It's therefore unsurprising that investors appear to be viewing Trojan's and Deitchle's purchases as votes of confidence for BJ's Restaurants' prospects and bullish calls on its stock. But investors should complete their own analysis of the company's fundamentals. In doing so, they'll find a restaurant chain that's struggling to contain rising costs, which are weighing on its bottom line.

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.