O'Reilly Automotive board chairman David O'Reilly recently sold 150-thousand shares of company stock for more than $ 4 million.

"Interestingly, another board member, David's sister, Rosalie O'Reilly Wooten, also in late August sold off a good number of shares,” says Eric Olson, Springfield Business Journal editor.

She sold more than 20-thousand shares for $625-thousand.

Selling of shares though isn't that unusual.

"These transactions happen on a daily basis,” says Olson. “Not often to this magnitude of Mr. O'Reilly's 150,000 shares. It's just part of ebb and flow of stock market."

It's been a big year for the company.

In July, O'Reilly Automotive acquired Phoenix-based CSK Auto Group for one billion dollars. "This deal comes on the heels of that and also a really good second quarter where they saw sales increase almost 10 percent," says Olson.

O'Reilly Automotive has 133 million shares outstanding, so while it was a big sell for the individual shareholders, it's just a small dip in the big picture.