For Apple, the release of two new iPhone models has already resulted in nearly double the sales of previous releases.
Apple said on Monday that it sold 9 million new iPhones over the first weekend that the phones, the iPhone 5S and iPhone 5C, were on sale. That compares with 5 million iPhone 5 smartphones sold last year in that model's first weekend.
It was the first time Apple had released two new iPhones instead of one. It was also the first time it released iPhones at the same time in multiple countries, including China.
"This is our best iPhone launch yet," said Timothy Cook, Apple's chief executive, in a statement. He said the company had already sold out of the more expensive model, the iPhone 5S, but more shipments were on the way.
The company did not say how many of each model were sold, but it had expected the iPhone 5S, the more expensive one, to be the more popular. Apple allowed customers to place early online orders for the cheaper 5C but not the 5S because of expected supply constraints.
Sales of the new iPhones topped analysts' expectations. They had predicted Apple would sell 5 million to 8 million.
The strong sales should give Apple a much-needed lift. Over recent quarters, its revenue has been flat and its profit growth has slowed. And its stock has taken a beating on Wall Street amid investors' concerns that the company had lost its ability to innovate after the death of its visionary co-founder, Steve Jobs. Its stock opened Monday with a gain of about 5 per cent.
The sales figures apparently exceeded even Apple's expectations. The company said that while it had forecast $US34 billion ($36 billion) to $US37 billion in fourth-quarter revenue, it now expected revenue to be towards the high end of that range.