People are slowly realizing that Apple's new iPhone 6, expected in the fall, is going to be so much more massive than iPhone 5, iPhone 5S, and iPhone 5C were — and it's showing in the stock. Apple stock is nearly at $640 this morning. It started the year at $553 and hit a humbling low of $499 in January 2013 when people began to suggest that maybe Apple was losing its mojo:

Yahoo Finance

Since then, it has become clear that iPhone 6, with its rumored bigger screen, is likely to drive a massive number of phone upgrades.

For years, Samsung has creamed off smartphone customers with its Galaxy S and Note models, which offer a nice big screen. Apple has been smiling through gritted teeth as its users have had to make do with a small-in-hindsight 4-inch screen. Apple has known its sales have been hurt by its small screens for years, and even produced some internal documents fretting over the issue.

We showed you this chart yesterday, which says that 80% or more of current iPhone users are due for a new phone because they're using old iPhones that are near the end of their useful lives:

UBS believes that will drive a massive buying cycle, and Apple will sell 166 million phones this fiscal year, up from 150 million last year, according to a recent note to investors.

There's only one variable, and that's whether Apple will launch a super-large 5.5-inch iPhone in addition to a 4.7-inch model. The larger screen would have it compete more squarely with Samsung's high-end phones; the smaller one still leaves it a lot smaller than a Samsung. You can see a leaked photo of the 4.7 inch iPhone 6 here.

If the 5.5-inch does happen though, it sounds like Apple may wait until early 2015 to launch it.

Here's our comparison chart: