The new iOS 9 software is now on more than 50 percent of iPhones, iPads and iPod Touches, according to Apple.
The company announced the figure on Monday morning, proclaiming it the fastest iOS adoption rate ever.
Apple measures iOS adoption based on the number of devices that visit the Apple Store on a given date.
The 50 percent mark is based on Apple's App Store stats as compiled on Saturday, September 19, the fourth day into the rollout of iOS 9.
"iOS 9 is also off to an amazing start, on pace to be downloaded by more users than any other software release in Apple's history," Philip Schiller, Apple's senior market VP, said in a press release on Monday.