The reach of Amazon.com (NASDAQ:AMZN) continues to expand. Though Amazon stock has pulled back from the $1 trillion mark, the company itself continues to grow.

The most recent sign of Amazon’s expansion came on Tuesday. CNBC reported that the company is planning eight new Alexa devices. Amazon clearly is moving beyond its initial Echo smart speaker offering — and attempting to make Alexa the gold standard in voice assistants.

AMZN stock did rise nicely in Tuesday trading, though likely more due to investors buying the ‘dip’; Amazon stock has pulled back about 7% since the stock cleared the $1 trillion mark earlier this month. And admittedly, Alexa devices on their own don’t justify much of AMZN’s current $940 billion market cap — or suggest that Amazon will continue its torrid run.

But Amazon’s strategy here is an echo (no pun intended) of its overall plans. And the advanced rollout of Alexa devices is something investors in other stocks need to watch as well.

The New Alexa Devices

CNBC’s report suggests “at least” 8 new voice-controlled Alexa devices are on the way by the end of 2018. Amazon is releasing a microwave oven, stereo components including an amplifier and a subwoofer, along with “an in-car gadget”.

It’s a notable effort for Amazon, a company that — as I wrote two years ago — hasn’t had the best track record in hardware. (Remember the Fire Phone?) The move significantly expands the reach of Alexa in both the home and the car. As CNBC pointed out, it also seems to augment the recent acquisition of ‘smart doorbell’ maker Ring and Amazon’s partnerships with homebuilders and ‘smart home’ designers.

What it shows, from a broad standpoint, is that Amazon is starting to put some serious muscle behind Alexa. And that could spell trouble for a number of rivals.

Can Alexa Drive AMZN Higher?

It’s a sign of Amazon’s heft that Alexa still has a chance to win the voice assistant race — despite the fact that Amazon had a somewhat late start in the space. Apple (NASDAQ:AAPL) released Siri back in 2011, and Siri still dominates voice assistant market share, at 46%. Alphabet’s (NASDAQ:GOOGL,GOOG) Google is second.

But Alexa has garnered 10% of the market — without the benefit of a phone. And as Amazon expands Alexa’s reach, that share can grow.

That doesn’t make AAPL or GOOGL stock a short. But it’s another aspect in which Amazon stock is starting to gain the attributes ascribed to its other mega-cap tech peers.

First, it was advertising. Google and Facebook (NASDAQ:FB) are dominant, but Amazon now has a multi-billion-dollar opportunity. Now, Alexa is part of Amazon becoming a ‘platform,’ which is a key reason why many investors remain bullish on GOOGL and AAPL at the highs.

What’s Good for AMZN Stock Isn’t Good for Others

There are other stocks potentially in Amazon’s crosshairs. Recent IPO Sonos (NASDAQ:SONO) tumbled 7% on Tuesday — though the extent to which the Amazon news drove that decline isn’t clear. SONO was already moving in the wrong direction after a Q3 earnings miss last week.

Roku (NASDAQ:ROKU), meanwhile, continued to rise on Tuesday, which is an interesting response from the market. Roku’s strategy involves home sound efforts of its own with the plan of providing more than just a streaming device. Amazon’s initial expansion of Alexa devices is another area where it is competing with Roku; earlier this year, AMZN teamed up with Best Buy (NYSE:BBY) on smart TV sales.

Again, Alexa isn’t necessarily a game-changer for Amazon stock. But it can be a problem for its rivals — and another small piece of the seemingly unstoppable bull case for AMZN.

Is AMZN Too Expensive?

I’ve been a long-time bull on AMZN, but I do wonder just how much steam is left in the rally. New Alexa devices don’t necessarily fix that problem.

But from a broader standpoint, Amazon’s continuing moves into new markets — and its general track record of success — do support the bull case for Amazon stock.

The stock does look absurdly valued on an earnings basis, but Amazon isn’t focused on earnings. It’s focused on growth.

And as long as the company keeps having success with efforts like Alexa and Amazon Web Services (among many, many others), that probably will be good enough for investors. Alexa may not drive AMZN back to a $1 trillion-plus valuation — but the strategy behind it just might.

As of this writing, Vince Martin has no positions in any securities mentioned.