Operating income at Amazon soared in the first quarter of 2019, jumping to $4.4 billion, from $1.9 billion, in the first period of 2018. The increase easily beat analysts' expectations. The earnings gain came on a 17% revenue increase, to $59.7 billion.

About half of Amazon's profits came from its cloud business, AWS, and the other half from its North American segment. The international group lost a small amount of money.

Sales through Amazon's online stores grew at a relatively modest 9.3% in the quarter, while sales of third party sellers rose 19.3%. Subscription services revenue, which includes fees from Amazon Prime plus subscriptions for audiobooks, digital video, e-books, and digital music, rose 38.7%.

In a conference call, executives said that Amazon is investing $800 million to upgrade its core Prime shipping option from two days to one day. For the second quarter, Amazon said it expects revenue to grow between 13% and 20% over last year's second quarter sales. Operating income is projected to be between $2.6 billion and $3.6 billion, compared to $3.0 billion in the second quarter of 2018.