Following a huge run-up in 2019 and the first half of 2020, shares of Apple (NASDAQ:AAPL) have taken a breather recently. The tech stock is down 17% from an all-time high of about $138 this summer.

Is weakness in the tech giant's stock a buying opportunity? Or should investors hope for an even bigger sell-off before they take a position in the iPhone maker?

iPhone 12 devices in an Apple store.

iPhone 12, 12 Pro, and 12 Pro Max. Image source: Apple.

Apple's business is stronger than ever

It's difficult to criticize Apple's business. The company generated $275 billion of revenue in the trailing 12 months, up from $260 billion one year earlier. Meanwhile, Apple raked in an incredible $73 billion of free cash flow (cash from operations less capital expenditures).

One potential critique an investor might bring up is the company's decline in iPhone revenue in Apple's most recent quarter. iPhone revenue fell 26% year over year during the period.  But Apple bulls would quickly point out that the tech company was up against an unfair comparison during the period since this year's iPhone launch was delayed by pandemic-related supply chain challenges. In fact, if you rewind one quarter -- when Apple wasn't up against an unfair comparison -- Apple demonstrated growth across every product segment and every geographic region. In the company's most recent quarter, every segment other than the iPhone saw strong double-digit growth despite supply chain constraints for some products. Management went as far as to confidently forecast that its iPhone segment would return to growth during the current quarter.

Then there's Apple's $192 billion of cash and marketable securities. Even when subtracting out low interest rate debt, excess cash is $79 billion.

With both a strong business and a healthy balance sheet, the company is unsurprisingly returning lots of cash to shareholders. In the fourth quarter of fiscal 2020 alone, Apple returned $22 billion to shareholders through dividends and repurchases.

But what about that pricey valuation?

Apple's demonstrating broad-based growth, generating more than $70 billion annually in free cash flow, and sitting on a mountain of cash. But is it worth $2 trillion? This is approximately where the company's stock price today puts its market capitalization.

Workers prepare iPhone 12, iPhone 12 Pro, and iPad Air boxes for shipment at Apple’s distribution center in Carlisle, Pennsylvania.

Apple distribution center. Image source: Apple.

Unfortunately, even though Apple looks well positioned to deliver double-digit earnings growth in the coming years, the stock's valuation is too steep to make this a no-brainer buy today. Shares currently trade at 35 times earnings -- a steep premium that prices in strong growth for years to come.

Sure, Apple stock may be a good buy for investors looking for dividend income. Apple currently has a dividend yield of 0.8%, and it's grown that dividend payout every year since it was initiated in 2012. But for investors looking for strong share price appreciation over the next five years, it might be worth waiting to see if the stock falls further before buying.