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By Harriet Taylor, CNBC

After Apple CEO Tim Cook introduces the new iPhone on Wednesday as expected, Apple's stock is likely to close the day down, if history is anything to go by.

Over the past 10 iPhone announcements — going back to Steve Jobs' introduction of the first iPhone on Jan. 9, 2007 — on the day of the big reveal, Apple ends the day negative 80 percent of the time, new data from Kensho's Bhavesh Dayalji and CNBC's quantitative analysis team show.

But the day after the iPhone announcement, Apple is positive 70 percent of the time by an average of almost 1 percent, according to the Kensho study.

In a separate study on Tuesday, UBS said Apple share prices will likely rally after Wednesday's expected announcement and then fade after the launch.

The iPhone 5 announcement was the first major announcement after Tim Cook took over as CEO. The iPhone 6 and 6 Plus announcement was packaged together with the introduction of Apple Watch and Apple Pay, helping to deliver a 3.07 percent next day bump to the stock.

This year, expectations for the new iPhone are somewhat muted, so the introduction of even a modest upgrade — like better iPhone battery life — could drive the stock higher, said Piper Jaffray analyst Gene Munster.

Here is what analysts and Apple watchers are expecting Apple's new iPhone to look like: an updated design — with the biggest change likely to be the removal of the headphone jack — a new black color, tweaked antenna lines, new cameras including a dual lens camera for the iPhone 7 Plus, a doubling in storage capacity of the entry level device to 32G, and an increase in storage capacity to 256G for the most expensive device.

"We're not saying iPhone 7 is a game changer, we are saying it's going to be a solid upgrade, high quality product that will return the iPhone and Apple to growth in 2017," said Drexel Hamilton analyst Brian White. "I think you are still in this gloom-and-doom cycle, but off the bottom.”

Apple's stock, profits and sales likely bottomed in the second quarter of fiscal year 2016 and Wednesday's event could mark a turning point, he said. Though people have continued to doubt Apple's ability to innovate, they will find that the company is simply suffering because the iPhone 6's success has been impossible to match.

"A healthy upgrade — that's really all we need," said White.

Read More From CNBC: Why Apple Needs a New Watch: Sales Are Plunging