Apple stock is jumping because the iPhone 7 is exceeding expectations

Apple stock is up nearly 3% on Tuesday as investors cheered signs that the company's latest iPhone is off to a strong start.

Two major American wireless carriers, Sprint and T-Mobile, announced on Tuesday that iPhone 7 presales were exceeding expectations. T-Mobile said the iPhone 7 set a single-day sales record, and Sprint said that iPhone 7 and iPhone 7 Plus preoders were up more than 375 percent.

Additionally, the first batch of iPhone 7 reviews were published by the tech press and mainstream media, and although they weren't glowing, many professional gadget reviewers believe the iPhone 7 is nonetheless the best phone on the market.

Previously, Apple advised that it was not planning to release first-weekend presale numbers, a data point analysts traditionally used to gauge how big an iPhone launch is going to be. Apple's decision not to release presale orders marked a change from its previous practices, raising concerns among some investors that the move reflected the company's tempered expectations at a time when revenue from the iPhone business is experiencing its first ever decline.

The iPhone 7 officially hits store shelves on Friday.

Here's the chart: