Amazon's share price fell more than 13% in after-hours trading on Thursday after its sales in the fourth quarter missed forecasts.
The online retail giant posted a 21% rise in sales and record profits in the final quarter, but that still wasn't enough to impress investors, who had expected net sales of $200 million more than the $35.75 billion it reported.
Its profits for the fourth quarter more than doubled to a record $482m (£335m). But over the whole year, profits of $596m also missed expectations as operating costs jumped 18%.
But there is positive news in that it is the third consecutive quarter in which Amazon has posted a profit, and the first time it has done so since 2012. Amazon's key issue in recent years has been convincing investors of its profitability.
Sales in the whole of 2015 were up 20% to $107bn - the first time it has passed the $100bn mark. Sales of its Amazon Prime membership also jumped by 51%
