For Apple, the release of two new models of the iPhone has already resulted in an increase in the number of sold previous models almost twice.

On Monday, Apple said that it sold nine million new iPhones for the first weekend, after the iPhone 5S and iPhone 5C models were on sale. This compares with the five million iPhone 5 sold last year for the first weekend.

The release, held on Friday, is different in that Apple first introduced two new iPhones at once, instead of one. It was also the first time that new models were presented simultaneously in many countries around the world, including China.

"For now, this is our best release of the iPhone," said Timothy D. Cook, Apple's chief executive, in a statement. He also noticed that the company had already sold off a more expensive model, the iPhone 5S, but new deliveries are expected.

The company did not say how many units of each model was sold, but it is expected that the iPhone 5S, a more expensive model, will be much more popular with the younger 5C model. Apple allowed customers to place online pre-orders for a cheaper 5C model, but not at 5S (due to expected delivery difficulties).

Sales of the new iPhone exceeded the expectations of analysts. According to their forecasts, Apple had to sell between 5 and 8 million iPhones.

Successful sales should give the company much-needed momentum. Over the past quarters, the company's revenues were fairly average, without ups, and profit growth slowed. On Wall Street, Apple shares fell due to investor fears that the company has lost its predisposition to innovation after the death of its fantasy-rich co-founder, Steve Jobs. The company's shares opened Monday with an increase of about 5 percent.

"It's pretty clear that the rumors about Apple's demise are wrong," said Lawrence Isaac Balter, chief market strategist at Orejkle Investment Research, who have clients with Apple shares.

Apparently, sales figures exceeded expectations even of Apple itself. After the announcement of new models, the company released an updated financial guide for investors. Apple said that although they previously forecast between $ 34 and $ 37 billion in revenue, it is now assumed that revenue will be closer to the highest expected amounts.