Amazon.com investors drove shares down sharply on Thursday due to weakness in the retailer's cloud computing unit and lower-than-expected forecasts for first-quarter revenue and profit.Amazon's shares fell as much as 5% in extended trade after the fourth-quarter earnings report,

Amazon's beat Wall Street's overall expectations with $187.8 billion in net sales, up 10%, and came in well ahead on the bottom line, with earnings of $1.86 per share, vs. expectations of $1.48 for the fourth quarter.

Amazon shares slid after the online-retail and cloud-services giant offered a first-quarter outlook that came up short of Wall Street’s expectations while forecasting bumpy trends in its cloud business.

Amazon.com topped Wall Street estimates for quarterly revenue on Thursday, as strong sales over the holiday shopping season boosted its retail business, helping offset weakness in the cloud computing unit.