Is Apple "yesterday's stock"?

That's the term one portfolio manager used to describe the world's most valuable public company.

Speaking to BNN on Tuesday, Norman Levine, managing director at Portfolio Management Corp., raised concerns over the company's future.

"When Steve Jobs died, the great innovation - I believe - came to an end and now it’s more incremental than the new stuff coming out," Levine said. "The smartphone market which is where they dominate now, the handset market has been a graveyard for companies: BlackBerry, Nokia, Motorola. And hopefully Apple doesn’t fall into that."

Levin said he likes to own what he calls "today stocks" and "tomorrow stocks."

"Apple, to me, is a yesterday stock," he said. And this is from somebody who owns almost all of their products."

In April, Apple announced its quarterly revenue fell for the first time in 13 years, as iPhone sales fell from a year earlier.

Apple sold more than 51.2 million iPhones in the first three months of 2016 -- racking up $10.5 billion in quarterly profit. That was more than many analysts expected, but still fewer than the 61 million iPhones sold a year earlier.

In recent weeks, some analysts have raised concerns over what Apple will do next, as their latest iPhones are similar to previous models, while overall smartphone sales begin to slow worldwide.

So can Apple come out with the next great product?

A blog post by New York web and iPhone developer Marco Arment, who was the lead developer for Tumblr for four years, hypothesizes about Apple going down the same path as BlackBerry, who was once the leading global smartphone marker.

"BlackBerry’s success came to an end not because RIM started releasing worse smartphones, but because the new job of the smartphone shifted almost entirely outside of their capabilities, and it was too late to catch up," Arment writes. 

While much of Apple's success revolves around the iPhone, Arment points out that a number of other technology giants including Google and Facebook are making major investments in artificial intelligence and virtual reality

"Today, Amazon, Facebook, and Google are placing large bets on advanced AI, ubiquitous assistants, and voice interfaces, hoping that these will become the next thing that our devices are for," Arment writes. "If they’re right — and that’s a big 'if' — I’m worried for Apple."

With files from The Associated Press