Apple (AAPL -1.10%) was slammed last week, with shares sliding more than 4%. In fact, the stock came just $0.68 from its 52-week low on Friday. Though the stock has regained some ground this week, there's no denying that Apple has taken a beating since its September 2012 high around $700 per share. At these levels, the stock has officially entered value-investing territory. Three metrics, in particular, paint a mind-boggling picture of a severely undervalued, highly profitable stock.

Share of profits
Though Apple's three-month average market share of smartphones in the U.S. was up sequentially in February 2013 compared to November 2012, according to comScore, the company is undoubtedly losing market share on a year-over-year basis. Apple's share of U.S. smartphone sales in the three-month period ending February 2013 declined to 43.5% from 47%. Meanwhile, Google's Android picked up the slack as its market share rose from 45.4% to 51.2%.

To be fair, Google's Android is a free mobile operating system, or OS, that is available to any smartphone manufacturer. Nevertheless, Apple's share of sales is declining.

This is where the first mind-boggling metric comes in. Though Apple is losing market share, its share of profits remains enormous. In the fourth quarter of 2012, for instance, Apple grabbed 72% of worldwide handset profits, according to Canaccord Genuity. Even more notable, that 72% of worldwide profits was achieved on just 21.7% of sales.

Market growth
Bears continue to line up to throw tomatoes at Apple, but no one can deny the enormous and fast-growing markets that Apple operates in. "Gartner expects the smartphone market to essentially double from 2011 to 2014, so Apple could see tremendous revenue growth even if it only grew at the market rate," Morningstar analyst Brian Colello pointed out. Furthermore, tablet shipments are expected to grow by 70% in 2013 compared to 2012, according to the IT research company. Gartner also projects a sustained upward trend in sales, growing by 32% annually between 2012 and 2017.

FCF yield
Despite Apple's massive share of worldwide handset profits and a spectacular market outlook, the stock trades at an unjustifiably conservative valuation.

In a recent article, I compared Apple to slow-growth megacap stocks, including McDonald's, Wal-Mart, Microsoft, and Intel, using the free cash flow yield -- a great indicator of a stock's value. Of these four companies, the only one with a free cash flow yield as high as Apple's (the higher it is, the cheaper the stock) was Microsoft -- a company with stalling growth, whose Windows-based PC sales continue to decline. Apple's FCF yield of 11.3% was more than twice as high as Wal-Mart's and McDonald's FCF yields, and 400 basis points higher than Intel's.

Keeping the faith in strong fundamentals
It's easy to point fingers at CEO Tim Cook or to criticize Apple for lack of innovation, but there is no denying the cash the company is producing. With indisputable leadership in terms of profits and enormous growth expectations ahead, Apple should continue to rake in considerably more cash than it's paying out. At its current levels, Apple is a steal.