On Thursday, Amazon.com announced that Amazon Web Services generated $2.4B in revenue during Q4 of 2015, or year over year revenue growth of 69%. The Q4 year over year growth rate declined from Q3 and Q2 of 2015, which recorded year over year growth rates of 78% and 82% respectively. Nevertheless, Amazon Web Services brought in a whopping $7.88B for the entirety of 2015, meaning that it is now fundamentally an $8B business. Operating income for Q4 was $687M and approximately $1.9B for the entire year. The $687M in operating income for Q4 2015 constitutes an increase in comparison to $521M in Q3 and $240M for Q4 of 2014. Amazon’s announcement of $2.4B in quarterly revenue represents the highest quarterly revenue figure for Amazon Web Services in its history, exceeding the $2.08B recorded in Q3 of 2014. Despite impressive financials for Amazon Web Services, shares of Amazon tumbled on Thursday after news that it had missed its earnings estimates and continues to operate on razor thin margins. Regardless, Amazon Web Services remains the fastest growing business unit within Amazon.com.