5G is here, and mobile service providers are heavily advertising the benefits of upgrading to a new device that can take advantage of the next-gen mobile network. Consumers are listening. Smartphone sales were up 26% year over year during the first quarter of 2021, according to tech researcher IDC, and some estimates point to over half of those sales being 5G-equipped devices.

The upgrade cycle is just getting started, though. Lots of work still needs to be done to continuously improve the network infrastructure, and most consumers around the globe don't even have access to 5G yet -- let alone own a 5G device. That being said, Micron Technology (MU 0.34%), Ciena (CIEN 0.34%), and Apple (AAPL 1.92%) are three stocks that stand to benefit in a big way from the 5G enthusiasm in the coming years. Here's why these three stocks are a buy right now. 

Someone laying on a floor using a smartphone.

Image source: Getty Images.

1. Micron: Memory chips are a basic staple of all things tech

Memory chipmaker Micron will feature prominently during the 5G upgrade supercycle. Semiconductors that store data are a basic commodity in most electronic devices these days, but 5G demands more storage capacity than ever before. From the data centers that act as the central nervous system of a mobile network to the cell stations that convert a network into wireless signal to smartphones and other devices themselves, these basic chips play an important role.

Micron is a leader here, developing ever-smaller components that can handle greater data capacity. And after a couple of years of sales drought (caused first by the U.S.-China trade war, then compounded by the pandemic), Micron's revenue is quickly rebounding as spending on 5G ramps up. Second-quarter fiscal 2021 (the three months ended March 4) sales were up 30% from a year ago, and adjusted earnings per share were up 117%.  

Because memory is a basic commodity tied to manufacturing, Micron's sales are highly cyclical. It's benefiting from a massive surge in demand for 5G and related tech at the moment, and a global chip shortage is raising the prices Micron can charge its customers. Eventually, though, demand will ease and Micron's sales will moderate. But the current upcycle has no end in sight yet. Between new smartphone sales and 5G network construction, 2021 is shaping up to be a very good year for Micron. 

Micron stock currently trades for just over seven times one-year forward expected earnings per share. If the current 5G upgrade cycle lasts into 2022 and beyond, there's lots of upside for this basic semiconductor industry stock. With shares trading on the cheap, I'm a buyer right now.  

2. Ciena: Networking activity is back on the rise

While 5G is all about speedier mobile service for consumers, network operators have to contend with lots of new traffic behind the scenes. That's where Ciena comes in. The company sells optical networking hardware that increases the capacity for data flowing through the web, as well as software that helps network operators manage their systems. 

After the initial buildout of 5G in 2019 and 2020, mobile network providers and other internet infrastructure companies tapped the brakes on new construction. The pandemic didn't help matters last year either. Trailing-12-month sales for Ciena have slumped about 10% from their all-time peak last summer as a result. Fiscal 2021 second-quarter revenue was down nearly 7% from a year ago. However, at $834 million, quarterly sales were up 10% sequentially, and the outlook for the third quarter implies Ciena could return to year-over-year growth. Management had previously forecast as much as 3% growth for full-year 2021, so the company looks like it's on track to deliver on its financial goals as network buildout resumes.

With construction to expand and improve 5G service an ongoing process, Ciena is a promising slow and steady growth play for the long term. And as network operator spending recovers this year and next, Ciena's profit margins will improve. In fact, though sales were still off from all-time highs, free cash flow actually increased year over year in the second quarter to $166 million (it was $85.5 million a year ago) -- helped by the sale of higher-end networking hardware and steady increases in software use.  

After the latest update, Ciena trades for just 19 times trailing-12-month free cash flow. With a return to sales growth imminent and 5G demanding network upgrades and more use of Ciena's infrastructure management software, shares look like a great long-term value right now.  

3. Apple: Smartphones now, more 5G devices later?

Apple is already the world's largest tech company, having benefited more than anyone else out there from the smartphone boom of the 2010s. Consumers upgrading to new 5G-ready iPhones are propelling Apple even higher, though, and the tech titan could have plans in the works that could also get a boost from the rollout of 5G.

But let's start with the most recent quarter: Sales surged 54% higher in the fiscal second quarter of 2021, driven by a 66% gain in iPhone revenue. Earnings per share more than doubled, up 119%. Operating profit was $24 billion, $23 billion of which was returned to shareholders via dividends and share repurchases. Speaking of dividends, Apple's quarterly payout was increased by 7% and another $90 billion added to the existing share repurchase plan, highlighting the strength of the business to return higher amounts of cash to investors over time.

Apple could just be getting started at the dawn of the 5G era. Android is still the dominant mobile operating system around the globe, so there are lots of new users it could pick up with its latest and greatest iPhone 12 lineup (the first models featuring 5G connectivity). Further down the road, 5G could be an integral piece of other technologies like virtual reality and vehicle autonomy. Rumors abound that Apple is working on its own virtual reality headset and a car.  

But for right now, the 5G network upgrade bump for the iPhone is more than enough to keep this stock steadily rising. Apple currently trades for 24 times trailing-12-month free cash flow, a metric that's sure to improve as the company starts to lap the depressed financial results from last spring at the onset of the pandemic. Now looks like a great time to buy more Apple stock.