Shares of BlackBerry (BB -1.09%) have fallen 25% over the last six months. The enterprise software and Internet of Things specialist nurses a $5 billion market cap, far below what once was the largest business (by market cap) in Canada. And despite all the market gloom, BlackBerry's trailing losses are shrinking -- isn't this a classic "buy" signal for a turnaround stock?

In a word, no. Here's why.

Two young business people expressing confusion in front of a computer screen.

Image source: Getty Images.

The primary problem

I'll give you some numbers to crunch in a minute. First, you should know that BlackBerry needs new management.

Sure, John Chen is a huge upgrade from the two-headed CEO position that preceded him. You can't blame Chen for losing BlackBerry's iron grip on the early smartphone market, because it was too late to turn that ship around by the time he grabbed the reins.

But that was five years ago, and Chen still has failed to come up with a workable business plan. In theory, I like the company's focus on high-margin software development and the specialization in supporting the Internet of Things for enterprise customers. Separately, these ideas make sense. Together, I'm not so sure.

Compare and contrast

The best example of a similar approach comes from General Electric (GE 1.99%), where it's known as the Industrial Internet of Things (IIoT). Add sensors and networking to a slew of industrial components and machinery, use them to collect and analyze operating data inside the machines themselves, then sit back and count the profits.

But it didn't work for GE. The centennial industry giant is abandoning the IIoT, which never really pulled its own weight. That's hardly GE's only problem these days, but the IIoT was supposed to save the conglomerate's bacon. That stock has plunged 56% lower in 52 weeks amid shrinking profit margins and unpredictable top-line sales.

I'm bringing up GE because BlackBerry's Enterprise of Things is a similar idea and the two companies are showing similar results. BlackBerry has been working with negative operating margins and plunging top-line revenues throughout Chen's entire reign:

BB Revenue (TTM) Chart

BB Revenue (TTM) data by YCharts.

Stay away!

I can't even argue that the stock looks cheap at today's rock-bottom prices. BlackBerry reports negative earnings and cash flows on a trailing basis and the stock is trading at 56 times Wall Street's (overly optimistic, if you ask me) earnings projections for next year.

I would take a serious look at this stock when John Chen is replaced -- and even then with a skeptical eye. This company has a long and rocky history of mismanagement and missed opportunities, and it won't be easy to convince potential clients that all of that has changed.