Szkutak has served as Amazon’s (AMZN) CFO since he joined the company in October 2002, and in that role oversaw the internal audit, controller, treasury, and investor relations functions, as well as financial management of Amazon’s business units. He will work with his successor, Brian T. Olsavsky, over the next 10 months to transition the CFO responsibilities, Amazon said.

Olsavsky joined Amazon in April 2002, just a few months before Szkutak became CFO. Olsavsky, 51 years old, previously spent seven years at Fisher Scientific International in a variety of financial and business management roles.

Amazon’s stock has faltered this year, as some investors express concern about sharply higher expenses even as sales continue to rise in the double digits. The second-quarter loss of $126 million that Amazon reported earlier this summer was almost twice the average analyst estimate.

The retailer continues to generate headlines as it expands its business on a number of fronts. In just the past month, Amazon expanded its same-day delivery services to six new metro areas, reportedly picked a fight with Disney, launched a new card reader and mobile app, and paid $1 billion to acquire online social video company Twitch.