SEATTLE — Amazon posted a profit of $14.3 billion in the fourth quarter, nearly doubling year over year despite heavy spending to ensure prompt deliveries.

Amazon also announced it will help offset rising fulfillment costs by raising the price of Prime, increasing the annual fee for U.S. members by $20 to $139.

Amazon’s profit in the three months through December is due to the strength of its cloud computing business, Amazon Web Services. Earnings were also boosted by growth in its advertising unit as well as the rising value of its stake in Rivian Automotive following the electric vehicle maker’s initial public offering.

Revenue in the cloud computing business increased 40% to $17.8 billion, more than offsetting an operating loss in the rest of Amazon’s business. Online sales were down nearly 1% from the year-earlier period. The retail business has been crimped by labor supply shortages, higher wages and supply chain issues.

Amazon said it spent $23.6 billion on shipping in the fourth quarter, a 10% increase from a year earlier.

Overall operating income was cut nearly in half, to $3.5 billion, from $6.9 billion the fourth quarter of 2020.

Fourth quarter sales at Amazon’s brick-and-mortar stores were up 16% to $4.7 billion in the year’s final three months. Those revenues came mainly from its Whole Foods Market stores and exclude online grocery orders for Prime Now delivery or in-store pickup. Amazon ended the quarter with 511 Whole Foods stores, 23 Amazon Fresh grocery stores, 24 Amazon Go convenience stores, 33 Amazon 4-Star locations and 24 Amazon Books stores.

Guidance for the current quarter projects net sales increasing between 3% and 8% from last year’s level. Operating income is expected to come in between $3 billion and $6 billion, down from $8.9 billion in 2021’s first quarter.

The increase in the Prime membership fee takes effect March 25. Amazon last raised the cost of a Prime membership in 2018, with a $20 increase to $119 a year. Prime members in more than 90 metro areas get free one-day delivery on a variety of Amazon purchases. Other perks include streaming video content and cloud storage.

“When we look to do price increases, we take it very seriously. And we’re always balancing the value to customers versus the cost of supplying benefits,” Brian Olsavsky, Amazon’s chief financial officer, said during the earnings call with Wall Street analysts. “There will be always be some potential [subscriber] loss, but it hasn’t been large in the past, and we feel pretty confident in the value proposition of our Prime offering.