The Apple Store in Hamburg, Germany (© MAJA HITIJ, epa, Corbis)

At long last, Apple (AAPL) is finally in the green year-to-date in 2013. And while the stock has still woefully underperformed the S&P 500 ($INX), it's undeniable that the tech giant finally has some swagger back after some recent strength.

But what's next? Is Apple stock ready to push even higher, or just giving investors another head fake?

I'm convinced it's the former -- and that Apple stock is a buy for long-term investors.

No, Apple is not on its way back to the valuations of late 2012 when it topped $700 a share. The company has changed a lot since then, and so have expectations.

And yes, there's the risk of buying a top. Shares are up over 40 percent in less than six months, and tech broadly is starting to feel a bit frothy to many market watchers after a big run in 2013.

But Apple's run since July has been built on a number of very real improvements in the business that bode well in the long term for shares even if we may see volatility in the short-term.

Investors who think this is just a short-lived uptrend amid a choppy "new normal" for AAPL stock are not giving the company credit where credit is due. Here are 10 reasons to buy Apple now:

1. Valuation

Apple is at a 52-week high after its big run from the summer lows, but still has a reasonable forward price-to-earnings ratio (P/E) of less than 12. That's lower than the average forward P/E of about 15 for large-cap tech stocks in the S&P 500.

Furthermore, that P/E of 12 is only slightly higher than the typical range Apple traded in over the past few years -- and anyway, that E part of the equation was unfairly low as Apple in the past year has regularly lowballed analysts on its profit forecasts.

2. E-commerce

Tech giant Adobe (ADBE) broke down recent holiday e-commerce trends, and Apple was the runaway winner among mobile shoppers. According to Adobe, "iOS-based devices drove more than $543 million dollars in online sales, with iPad taking a 77 percent share. Android-based devices were responsible for $148 million in online sales, a 4.9 percent share of mobile driven online sales." Say what you want about overall market share, but Apple is the clear winner among people who actually spend money -- a much more valuable statistic to investors than adoption with no dollar signs attached. 

3. China

Last week, we finally got confirmation of a deal between Apple and China Mobile (CHL) to put the iPhone into the biggest telecom market in the world with access to some 700 million subscribers. Yes, Apple will still have to figure out how to connect with low-income consumers with its high-price devices. But Apple's China market share was just 5 percent to start 2013 -- meaning massive untapped potential.

4. Cash hoard

Everybody says it, so I will, too -- Apple is a cash cow.

Its stunning stockpile of $146 billion continues to grow and is a giant pile of untapped potential. And if the cash alone wasn't enough for you, Apple has shown it's willing to borrow on top of that. Apple raised $17 billion this year in a bond offering with rock bottom rates -- including $3 billion of debt at just 3.85 percent on its 30-year bonds. The cash is plentiful and debt is cheap, giving Apple a lot of dry powder for 2014 and beyond.

5. Buyouts

Buyouts are one use for that dry powder, and next year could be the time we see the first major Apple acquisition. Apple had been notoriously reluctant to buy out anybody, likely because of Steve Jobs' rather top-down view of the world, but the company has changed in many ways since Tim Cook took over. That includes shopping around. Apple's $200 million purchase of Twitter (TWTR) data provider Topsy recently could be the first foray into growth via acquisition -- something the company has ample cash to bankroll.

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