In late July, I said investors were looking at a “golden opportunity to buy Apple’s stock” after the iPhone maker’s shares declined 4%.

That drop followed a fiscal third-quarter earnings report that showed strong earnings and sales growth, but the company disappointed investors with a lower-than-expected outlook for fourth-quarter sales.

Since then, Shares of Apple Inc. AAPL, +1.57% tumbled 18% from $125.22 on July 22 to a 2015 closing low of $103.12 on Aug. 24, before recovering to $110.15 on Wednesday. So the shares are down 12% since I made my call. On Wednesday, the shares were down 1.9%, following Apple’s annual rollout of new products, including the iPhone 6s and 6S Plus, the iPad Pro and a new Apple TV streaming device.

Apple executives also discussed partnerships with several companies, including IBM, Cisco, Microsoft, in order to better orient the iPad Pro toward enterprise customers.

Follow:Apple event live coverage

Of course, I didn’t predict the S&P 500’s SPX, +1.05% 8% decline since July 22 either. It appears I was “early” in suggesting that Apple would be a good long-term investment. Then again, “long term” means being committed for several years, and not reacting to the day-to-day fluctuation of the stock market.

Apple’s stock has more than tripled over the past five years, but it hasn’t always been a smooth run. FactSet

A major concern for analysts following the fiscal third-quarter earnings announcement was the possibility that Apple could face pressure on sales in China, where economic growth seems to be slowing. Sales in China more than doubled to $13 billion in the three months ended June 27.

Read: Apple’s stock drop ahead of iPhone event could be good news for investors

Then again, Credit Suisse analyst Kulbinder Garcha said in a note to clients on Thursday that “there will be continued volatility around the supply chain, given concerns over China demand even if Apple does not seem to have been impacted yet.”

Apple sold 169 million iPhones during fiscal 2014. Garcha expects sales for fiscal 2015 to rise to 234 million, “expanding to 241 million (in 2016) before plateauing.” He said upgrades will provide a “healthy tail wind to growth,” with large-size iPhones penetrating 70% of the iPhone market by the end of fiscal 2016 from “sub-30% today.”

The numbers tell the story: Apple’s stock is cheap

Apple is, by far, the largest company in the world by market capitalization. The market value is $641 billion, with Google Inc. GOOGL, +2.07% coming in second place at $397 billion, if we include both the Class A and Class C GOOG, +2.39% shares.

Here are the 10 largest S&P 500 companies by market cap, including sales growth over the past 12 months:

Sales numbers have been adjusted by FactSet to exclude certain items, including revenue from foreign-exchange contracts.

Doubting Apple’s ability to keep up a strong sales-growth pace is nothing new, but as you can see, it leads the 10 largest S&P 500 companies, four of which are technology firms.

The difference is even more stark when looking at growth of sales per share:

We included Google’s Class A shares in this table, since the company split its shares into Class A and Class C in April 2014. The Class C shares are subject to dilution. Any further common shares the company issues will be Class C.

Apple’s continuing buybacks lowered its average fiscal third-quarter diluted share count by 5% from a year earlier.

Read:How Apple’s big events help its rivals

Buybacks have gotten a bad name, being seen as evidence that many companies lack innovative ways to expand their business with excess cash. Some may also use the buybacks simply to maintain the share count while doling out huge stock-based compensation packages to top executives.

Read:The real reason to worry about obscenely high executive pay

But in the case of Apple, the buybacks are shareholder-friendly, boosting already fantastic sales-growth numbers and earnings, as we’ll see below.

This table shows how much more money Apple is making than other large companies:

Only J.P. Morgan Chase & Co. JPM, -1.09% has posted faster earnings growth than Apple over the past 12 months, as the bank’s legal and other costs associated with the credit crisis have declined.

Here’s EPS growth over the past 12 months for the 10 largest S&P 500 companies:

For so many tech stocks, investors focus on sales growth rather than earnings growth. That is especially true for Amazon.com Inc. AMZN, +5.69% But Apple continues to achieve outstanding results in both areas.

But the naysayers have a lot of influence, as you can see when looking at price-to-earnings multiples. The S&P 500 trades for 16.7 times the weighted aggregate consensus earnings estimate, among analysts polled by FactSet. Apple always trades at a big discount to the S&P 500 by this measure.

Here are current-year price-to-earnings ratios for the same 10 companies:

J.P. Morgan is the cheapest stock on the list by current-year P/E, but large banks tend to trade at a considerable discount to the S&P 500. Apple is the second-cheapest, trading at just 12.3 times current-year estimated earnings.

Apple’s stock still looks like a bargain for long-term investors, despite years of doubt about its ability to continue boosting iPhone sales. Yes, it’s always the case that past results don’t determine how a company will do in the future, but there’s no denying that Apple continues to surprise analysts and investors by putting up strong numbers as the years go by.