What happened

Shares of electric-vehicle (EV) charging-station supplier Blink Charging (NASDAQ:BLNK) rode a bit of a roller-coaster today. After initially dropping 15% this morning, shares surged back up 7% before settling in to a gain of about 3.5%. 

Today provides an example of why investors in this sector need to start looking at the business fundamentals rather than just buying names in a hot industry. 

So what

Prior to the market open today, the EV sector looked like it was going to take a beating. And after the momentous run almost any name in the hot sector has had in the past month, that wouldn't have come as a huge surprise. 

Up arrow with fire indicating a hot stock sector.

Image source: Getty Images.

Some of the downward moves earlier in the day were due to company-specific news. Some may have been because of well-known investors deciding the huge run has to come to an end. Blink Charging shares experienced the volatility but didn't have any individual news to explain it. 

Now what 

Shares of Blink Charging have tripled in the last three months even after a 30% drop in the past week. That reversal began after a short-seller claimed the stock was way overpriced. 

Today, shares still trade for more than 140 times the company's sales. Electric-vehicle infrastructure is going to be a high-growth area. But that doesn't mean investors should just jump in at any price. Today's price action showed some investors are moving in and out on the whims of the market and the sector. 

Smart investors can add speculative companies to their portfolios in the right amounts and let the businesses develop without having to trade in and out. Some speculators in the EV sector aren't quite there yet. 

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.