Apple may have reported its best-ever September quarter yesterday and met Wall Street’s sales predictions, but investors seem less impressed. The company’s stock was down more than 2.5 percent today, falling as low as $593. For context, Apple hasn’t seen trading below $600 since July 30.

Apple announced it was expecting to set an all-time earnings record over the upcoming holiday quarter by selling $52 billion worth of products. The company also revealed, however, it expected to see lower profits owing to the lower margins and higher manufacturing costs of new devices like the iPhone 5, the fourth generation iPad and the iPad Mini. Tellingly, CEO Tim Cook said that the latter of which would have margins below average thanks to an “aggressive pricing strategy.”

Investors may also be concerned with Apple’s iOS device sales. Apple sold 46.2 million iOS devices during the quarter. That’s up 35.4 percent over Q4 2011’s sales of 34.1 million devices, but it’s down from Q3 2012’s 49.8 million, despite the fact that Apple launched the iPhone 5 this quarter. Overall, iPhone sales are up 57.5 percent year-over-year, but just 3.4 percent quarter-over-quarter.

While it’s clear Apple doesn’t think iOS device demand has peaked, rivals like Google and Samsung are catching up. Google Play now boasting nearly the same amount of apps the iTunes App Store has and Samsung shipped 56.9 million Android smartphones between June and September — more than double the amount of iPhones Apple sold in the same period.

On the tablet front, Apple’s clear shots at the Nexus 7 seem to indicate the device has found its footing as slick, but lower-priced alternative to Apple’s tablets. Microsoft could also pose a threat with its new line of Surface tablets. Tim Cook may have slammed the devices as confused, compromised products during Apple’s earnings call yesterday, but the launch of the device also drew a large crowd in New York, hinting the devices could see solid sales — at least initially.

Apple is still the undisputed market leader, but its beginning to look like the company will have to work much harder to hold onto its top dog status.