What happened

Shares of electric-truck start-up Nikola (NKLA -2.44%) were trading lower on Monday, as a good deliveries result from Tesla (TSLA -1.92%) failed to reverse a broader slump in electric-vehicle stocks. 

As of 11:45 a.m. EDT, Nikola's shares were down about 6.4% from Friday's closing price. 

So what

There was no major news driving Nikola's shares lower on Monday. I think the decline is best seen in the context of what has been happening to electric-truck stocks, and the electric-vehicle category in general, since about the beginning of February. 

NKLA Chart

NKLA data by YCharts

As you can see, Nikola's stock price has had a rough couple of months, but it's not alone. Investor enthusiasm for emerging companies in the electric-truck space has been fading as legacy vehicle makers with far greater resources gear up to launch electric trucks and commercial vehicles of their own. 

A Nikola Tre, a Class 7 electric semi, shown pulling a trailer on a highway.

Nikola is currently testing prototypes of its Tre electric semi. It hopes to begin production of the truck by the end of September. Image source: Nikola.

Now what

Broadly speaking, the smaller electric-vehicle companies' stocks tend to follow category leader Tesla's gyrations, but that wasn't happening on Monday. While Tesla shares were up on a better-than-expected deliveries total for the first quarter, the news didn't do much for Nikola or most of the other companies in the cohort. 

With no near-term catalysts for the stock on the horizon, investors may have to wait to see how well Nikola executes on its effort to get its Tre electric semi into production over the next several months.