Revenue decreased $8.3 billion or 9%, primarily due to the impact of the net revenue deferral from Windows 10 of $6.6 billion and an unfavorable foreign currency impact of approximately $3.8 billion or 4%. Windows 10 revenue is primarily recognized at the time of billing in the More Personal Computing segment, and the deferral and subsequent recognition of revenue is reflected in Corporate and Other. More Personal Computing revenue decreased, mainly due to lower revenue from Devices and Windows, offset in part by higher revenue from search advertising and Gaming. Intelligent Cloud revenue increased, primarily due to higher revenue from server products and cloud services and Enterprise Services. Productivity and Business Processes revenue increased slightly, driven by an increase in Office and Dynamics revenue.
Operating income increased $2.0 billion or 11%, primarily due to a decrease in impairment, integration, and restructuring expenses and sales and marketing expenses, offset in part by lower gross margin. Gross margin decreased $8.0 billion or 13%, driven by the decline in revenue as discussed above, and included an unfavorable foreign currency impact of approximately $3.3 billion or 5%. Productivity and Business Processes and More Personal Computing gross margin decreased, offset in part by higher gross margin from Intelligent Cloud.
Key changes in expenses were:
• Cost of revenue decreased $258 million or 1%, mainly due to a reduction in phone sales, driven by the change in strategy for the phone business, offset in part by growth in commercial cloud and search advertising.
• Impairment, integration, and restructuring expenses decreased $8.9 billion, primarily driven by prior year goodwill and asset impairment charges related to our phone business and restructuring charges associated with our phone business restructuring plans.
• Sales and marketing expenses decreased $1.0 billion or 6%, driven by a reduction in phone expenses and a favorable foreign currency impact of approximately 2%.