What happened

Proterra's (PTRA) mission is to advance electric vehicle (EV) technology in the commercial sector. The company builds electric buses, and also provides battery technology, drive trains, and charging solutions for heavy-duty commercial vehicles.

Now, a long-delayed EV from the best-known manufacturer in the space is going into production, and Proterra is about to face major competition in its fastest-growing business segment. Worries about what that will mean for the company helped drag Proterra stock down by about 9% this week as of early Friday, according to data provided by S&P Global Market Intelligence.

So what

In the second-quarter report it delivered in August, Proterra announced that revenue from its powered and energy products segment -- which includes battery technology and charging solutions -- soared by 122% year over year to $24 million. While that only represented about one-third of its total revenue for the period, that segment was the fastest-growing portion of the business. Total revenue grew 27% year over year.

But late last week, Tesla informed the world that it's just weeks away from the real-world debut of its electric heavy semi truck. CEO Elon Musk said the company will begin delivering Tesla Semi trucks to buyers on Dec. 1. The first customer to receive them will be PepsiCo, and there will likely be a large number of other major companies purchasing the vehicles. 

electric heavy truck plugged into charging station.

Image source: Getty Images.

Now what

Proterra shipped battery systems for 348 vehicles in the third quarter, a jump of more than 1,000% compared to the year-ago quarter. That was also a 21% rise compared to the previous quarter. But that period of sharp growth may soon come to an end if competing products hit the market and develop large customer bases.