Apple, once a company whose stock only knew a single direction, is in the midst of a painful decline. Today, for the first time since late 2011, the company’s stock traded below the $400 per share mark. The company ended the day’s trading at $402.59, a fall of 5.5 percent, or $23.09 per share.

That fall represents $21.8 billion in market valuation. In other words, Apple shed almost 22 Instagrams today.

The decline places Apple’s Price/Earnings ratio at roughly 9, implying that the market expects all but no growth from the company in the coming year; a normal PEG calculation, assuming the market is accurate, would imply that investors expect Apple to grow roughly 9% in the next year, but that figure doesn’t include Apple’s new quarterly dividend, lowering that figure by  perhaps 2%.

Indeed, it must be the growth rate that is spooking investors as nearly every other metric including share of iOS, share of smartphones in the US, share of profits of apps and hardware and many others are all looking very positive for Apple at the moment. The falling stock is a bet that Apple won’t be able to maintain growth, a bet that has proven awkwardly incorrect many times over the past few years.

In short, Apple, the once dynamo of growth, the creator of new product categories, the bullying firm that brought the music industry to heel, has lost some of the confidence of its investing owners. The company traded as high as $705 within the last 52 weeks. The company has therefore shed around 43% of its value in less than a year.

What has caused the loss of confidence? The narrative that surrounds the firm has become negative, based mostly on slowing unit sales growth. Two short excerpts make the point. BusinessInsider:

Apple’s iPhone 5 sales are “decelerating faster than expected,” says Jefferies analyst Peter Misek in a new note this morning. He says that Apple has cut its build orders to 30 million, down from 40 million.

The Telegraph:

Hon Hai Precision Industry, the world’s largest contract manufacturer of electronics, posted its biggest revenue decline in at least 13 years, pointing to slower sales of iPhones, iPads and computers.

That’ll take you down a peg.

Naturally, given lowered expectations, Apple is in a prime spot to prove its detractors wrong, and show strong financial performance. That said, the company may need a new product line to rekindle the levels of growth it all but recently enjoyed.

Image: Thinkstock