Oct 22, 2010 10:58 GMT  ·  By

Amazon has released its third quarter financial results, posting some very good numbers with growth in both terms of revenue and income. However, worse-than-expected estimates for the fourth quarter pushed stock prices down almost four percent.

"Net sales increased 39% to $7.56 billion in the third quarter, compared with $5.45 billion in third quarter 2009," Amazon said in a statement.

"Operating income increased 7% to $268 million in the third quarter, compared with $251 million in third quarter 2009," it added.

"Net income increased 16% to $231 million in the third quarter, or $0.51 per diluted share, compared with net income of $199 million, or $0.45 per diluted share, in third quarter 2009," Amazon said.

Amazon, the world's largest online retailer, has been growing steadily and is still seeing impressive numbers despite its size. The last quarter proves this, yet increased spending expected in the fourth quarter has made investors weary.

Amazon touted its Kindle Store and device in the financial report, despite the fact that it still doesn't offer separate numbers for the e-book store.

The third generation Kindle was introduced in the third quarter and Amazon says it's the fastest selling Kindle to date, surpassing sales of the first and second generation devices in the first 12 weeks of availability.

What's more, Amazon says that the Kindle is the best selling product overall on both Amazon.com and Amazon.co.uk.

The company is also saying that there are more than 720,000 books available for sale in the Kindle store, besides the 1.8 million public domain books available for free.

Investors were more interested in the forecast for the fourth quarter which wasn't particularly great. While revenue is expected to grow between 26 percent and 40 percent in Amazon's biggest quarter over the previous year, operating income could take a hit by as much as 24 percent, though the most optimistic figure shows a 18 percent growth over Q4 2009.