The US technology giant Apple has posted a record first quarter profit of $US13.1 billion ($12.4 billion).
The company's quarterly revenue hit $54.5 billion ($51.6 billion), which was very slightly below average analyst estimates.
Apple sold almost 48 million iPhones in the quarter, which is a record, but Wall Street was hoping for sales of around 50 million.
Sales of Apple's iPad came in at 22.9 million, which was roughly in line with forecasts.
The outlook has also concerned investors; Apple expects revenue to slip to around $US41-43 billion (circa $40 billion) in the second quarter as the initial boost from the iPhone 5's release fades.
"These results were OK, but they definitely raised a few questions.
Gross margin trajectory looks fine, so that's a positive, and cash continues to grow, but I think investors are going to want to know what Apple plans to do with [that] growing cash balance," Shannon Cross, an analyst with Cross Research, told Reuters.
"And other questions are going to be around innovation and where the next products are coming from, and what does [Apple's CEO] Tim Cook see in the next 12 to 18 months." 'Two-horse race' Apple boss Tim Cook's rhetoric remains upbeat, despite the concerns about iPhone sales and their popularity in Asian markets.
"We could not be happier with that.
In terms of the geographic distribution, we saw our highest growth in China and it was into the triple digits, which was higher than the market there," he told investors.
The results came out after the main market closed, however Apple shares fell 10 per cent in after-hours trade to $US463, wiping $US50 billion off the company's value.
Apple shares are now down by around a third from a record high in September, wiping around $US227 billion from the company's value since then.
Analysts say Apple risks slipping behind in its two-horse race with main rival Samsung.
"It's going to call into question Apple's dominance in the space.
It's still one of the strong players, the others being Samsung and Google.
It's still a two-horse race, but Android continues to grow rapidly," Sterne Agee analyst Shaw Wu told Reuters.
"If you step back a bit, it's clear they shipped a lot of phones, but the problem is the high expectations that investors have.
Apple's conservative guidance highlights the concerns over production cuts coming out of Asia recently."