In an unusual trend, Apple (AAPL) shares have been falling in the past 30 days in the run-up to the expected unveiling of the company's iPhone 6s and iPhone 6s Plus. 

Apple stocks usually surge in the weeks leading up to the release of its new devices but that's not the case with the iPhone 6s and the iPhone 6s Plus.

According to USA Today, shares of the company have "fallen 6.2% in the 30 days prior to Wednesday's widely anticipated announcement of the iPhone 6S." 

It is the first time the Apple stock has fallen prior to the launch of an iPhone.

However, Apple (AAPL) stock price closed at $112.31, up 3.04 dollars, or 2.78% on Tuesday, which could be the result of expectations about the new iPhones.

The Cupertino giant is tight-lipped on its upcoming iPhone but it is almost certain that it will be unveiled on Wednesday, 9 September in San Francisco, as it has sent out press invites for an event. The device is slated for release on 18 September, if the company were to follow its tradition.

The iPhone 6s is expected to sport a 4.7-inch screen, measure 7 mm thick and house a 1715 mAh battery, while the iPhone 6s Plus may have a 5.5-inch screen, 7.13 mm thick and powered by a 2750 mAh battery.

However, the devices are expected to share other specifications such as A9 chip, iOS 9, 32 GB internal memory, 2 GB RAM, and 12 MP main camera. Features such as Force Touch, stronger aluminium alloy chassis and improved fingerprint censor are also expected to be seen in the new devices.