What happened

Shares of Ceragon Networks (NASDAQ:CRNT) fell 11.7% in May 2017, according to data from S&P Global Market Intelligence.

So what

Ceragon's stock chart was a jagged affair last month, with lots of sudden reversals.

May started off on a good note, and Ceragon shares rose as much as 7.5% on preliminary moves to raise up to $150 million of cash in a stock offering. Then the company reported first-quarter results the next week, and share prices plunged 11% lower over the next two days. The negative momentum kept rolling from that point on, with only brief pauses on low trading volume along the way.

CRNT Chart

CRNT data by YCharts

Now what

That first-quarter report didn't exactly miss Wall Street's targets. Sales rose 27% year over year to $76 million, ahead of the $74.1 million analyst consensus. On the bottom line, the Tel Aviv-based provider of wireless backhaul networking systems saw adjusted earnings of $0.01 per diluted share while the Street would have settled for a breakeven result.

But Ceragon CEO Ira Palti painted a gloomy picture of upcoming growth opportunities. In a conference call with analysts, he said that telecoms probably won't need to start upgrading their backhaul networks to support new 5G wireless networks until the back half of 2019.

A technician fixing a bundle of wires.

Fiber optic networking might by the bane of Ceragon's existence. Image source: Getty Images.

That comment flies in the face of more optimistic 5G infrastructure forecasts from the fiber-optic networking sector, which could mean one of two very different things. One side could be right and the other one wrong, or everyone is giving an accurate forecast of backhaul structures shifting deeper into the fiber-optic market.

When you take a wider look at the evolving 5G wireless technology, it's easy to reach the conclusion that the implementation will be well underway as 2019 rolls around, and Ceragon's technology just won't be the preferred backhaul solution. If you agree and still want to invest in businesses poised to benefit from the 5G upgrade, you would be better off investing in fiber-optic companies instead.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.