e-Commerce firm Amazon has reported revenues of $17.4bn for the fourth quarter of 2011, an increase of 35% compared to $12.95bn in the same quarter in 2010.

The online retailer’s operating income stood at $260m in the fourth quarter, as against of $474m in the same quarter of 2010.

Net income decreased to $177m in the fourth quarter from $416m in the same period a year ago, registering a fall of 58%.

The key driver behind Amazon’s revenues in the fourth quarter were Kindle unit sales during the nine-week holiday period ending 31 December 2011, registering an increase of 177% compared to the same period in 2010.

The company expects its first quarter revenues of 2012 to be between $12bn and $13.4bn, or a growth of between 22% and 36% compared to the first quarter of 2011.

The company’s revenues for the full year of 2011 were $48.08bn, an increase of 41% compared with $34.20bn in 2010, while its operating income decreased by 39% from $1.41bn in 2010 to $862m in the year 2011.

On the other hand, its net income decreased by 45% from $1.15bn in 2010 to $631m in 2011.