All in all, it wasn't the quarter Amazon (AMZN 0.83%) shareholders were hoping for recently.

For the three months ended Sept. 30, the e-commerce giant turned $127.1 billion worth of revenue into income of $2.9 billion, or $0.28 per share. While sales were up year over year, earnings were down. Perhaps worse, the company's cloud computing arm suffered a sales slowdown that left its top line shy of expectations, and its e-commerce business continues to operate in the red.

The biggest driver of the stock's steep post-earnings sell-off, however, is guidance for the quarter now underway. Amazon is forecasting fourth-quarter revenue of between $140 billion and $148 billion versus analysts' consensus forecast of $155.1 billion.

The mostly bearish noise obscures a couple of more important bullish realities, though. First, the company's digital advertising business is still in high-growth mode, and second, Amazon's cloud services division remains wildly profitable and is growing just fine.

Amazon's doing better than headlines suggest

Contrary to popular belief, Amazon isn't an e-commerce outfit that also happens to dabble in the cloud computing arena. In terms of actual operating profits, it's a cloud computing company that also does e-commerce. This has been the case for a while now.

The graphic below puts things in perspective. Selling goods online may drive the bulk of its revenue, but Amazon Web Services accounts for the bulk of the company's operating income. It's accounted for all of its income this year, in fact, thanks to soaring e-commerce operating costs that are pushing this arm into the red.

The bulk of Amazon's earnings still come from its cloud computing arm Amazon Web Services.

Data source: Amazon. Chart by author. All dollar figures are in millions.

But even its cloud computing business is now bumping into a growth headwind. That's the prevailing narrative following last quarter's year-over-year top-line increase of only 27%, anyway, paired with another sequential drip in profits. However, that narrative doesn't necessarily tell the entire story.

On a percentage basis, yes, the pace of Amazon Web Services' revenue is comparatively slowing. On an absolute dollar basis, though, last quarter's $4.4 billion worth of year-over-revenue growth is right in line with long-term norms. It's unrealistic (and unfair) to expect Amazon's AWS arm to maintain sales growth at the ever-accelerating clip needed to maintain its historical growth rate, since the basis for the comparison is getting ever-bigger.

AWS and Amazon's advertising business continue to grow at a strong pace.

Data source: Amazon. Chart by author. All dollar figures are in millions.

Finally, there's another encouraging detail being drowned out by all the bearish chatter in response the company's recent report and outlook: Amazon's relatively nascent advertising business. Last quarter's $9.5 billion worth of ad revenue collected by Amazon.com's third-party sellers is 25% higher than the figure from the same quarter a year earlier, when this profit center first came into focus. As the graphic above makes clear, last quarter's advertising revenue growth pace is also the norm.

It's not clear whether the company's ad business is profitable or not. As a stand-alone operation it probably is, since digital revenue tends to be high-margin; in this case, Amazon's only related expense is managing an online-shopping website it would maintain whether or not it was running an advertising business.

This arm's revenue is also lumped into broad sales figures on the company's income statement, and not detailed when Amazon breaks out its North American, international, and Amazon Web Services results. However, it's not a stretch to suggest advertising is starting to offset the loss-making costs incurred in operating a bunch of warehouses, paying for freight, compensating employees, etc.

Pessimism is your buying opportunity

Don't get the wrong idea. Amazon's still got plenty of things to figure out. Namely, it still needs to get a handle on its logistics spending. AWS profits are shrinking, too. Prime's content costs are arguably racing out of control as well, with the company reportedly spending in excess of $700 million on a Lord of the Rings series that's only been met with so-so reviews. Then there's the lackluster fourth-quarter guidance.

Yet after last week's stumble dragged the stock back to a new 52-week low -- halving its peak value reached in November of last year -- it's time to start seeing the glass as half-full rather than half-empty and step into this time-proven name. It's got far more working in its favor than headlines are suggesting.

By the way, there's a distinct possibility that Amazon's tepid Q4 guidance is just a means of underpromising so the company can overdeliver when the company posts those results in January.