Amazon shares have surged after it reported much better than expected sales over the Christmas period and saw the number of Prime subscription members rise to 150 million.
The 13% shares rise in after-hours trading meant the online retail giant's market value soared to over $1tr (£750bn).
Sales for the three months to the end of December climbed to $87.4bn (£65.7bn), up 21% on the same period last year.
That included sales in North America alone that were $10bn higher than over the 2018 festive period.
For 2019 as a whole, sales were ahead by 20% at $280.5bn (£210.8bn), with profits 15% higher at $11.6bn (£8.7bn) - the latter despite the company's heavy spending on speedier deliveries.
Amazon founder and chief executive Jeff Bezos said customers had responded to improvements in its Prime loyalty club - which offers quicker delivery times as well as film and TV streaming, including some Premier League football games.
Mr Bezos said more people had signed up as Prime subscribers over the quarter than ever before, taking the total number to 150 million around the world - up 50% on the last time it disclosed numbers in 2018.
He said: "We've made Prime delivery faster - the number of items delivered to US customers with Prime's free one-day and same-day delivery more than quadrupled this quarter compared to last year."
Nicholas Hyett, equity analyst at Hargreaves Lansdown, said: "Amazon has repeatedly shown it's prepared to sacrifice short term profits for long term gains, and these results are no different.
"The group's delivered bumper sales in its retail business but seen profits only creep up as it invests in next day delivery.
"However, given the scale of investments taking place analysts had expected profits to reverse, and the fact they've improved despite the extra spending is testament to the quality of the business Jeff Bezos has created."