The electric vehicle (EV) sector has generally been hot since its inception, which is why it's a bit jarring that some of its top stocks recently grew cold. This week, more than a few manufacturers and associated businesses turned in uninspiring performances on the market.

Among the EV stocks thrown into reverse were vehicle producers Nikola (NKLA -8.46%) and Fisker (FSRN). According to data compiled by S&P Global Market Intelligence, both stocks saw declines at around the 15% mark over the period. Charging station company ChargePoint Holdings (CHPT -2.46%) also got stung, with a nearly 12% drop in share price in the Monday-Friday stretch.

Yellow lights in the rearview

There were scattered news items from individual EV companies that contributed to some of their declines. For example, on Wednesday Fisker announced a delay in publishing its latest set of quarterly results. The following Monday, ChargePoint was hit with a drastic price target cut from analyst Christopher Souther at B. Riley (to $5 per share from $11, although Souther did maintain his buy recommendation).

These events weren't enough to lower sentiment on the broader EV space, though. So what else was going on?

Investors continue to brood about the overall EV sales dynamic in everyone's favorite car-dominated large country, the U.S. According to estimates from Kelley Blue Book, unit sales came in at 313,086 for the third calendar quarter of this year.

That represented a year-over-year increase of almost 50%, but EV investors are a hard crowd to please. Those increases have been higher in quarters past, and the EV share of the wider auto market only crept up marginally (by 0.7%) from the second quarter. This has led to some fear that the once-explosive growth might be slowing.

Another factor is the recently ended United Auto Workers (UAW) strike. Largely seen as successful, the labor action has strengthened the position of the vast labor force required to make cars.

The UAW is a force inside the U.S. car incumbents like Ford, General Motors, and Stellantis -- the targets of the strike -- but it's surely eager to be a major presence in next-generation makers too. No less a personage than President Joe Biden called for unionization throughout the auto industry this week.

Choose wisely and hang on tight

EVs are indisputably the auto technology of the future, so folks bullish on the technology shouldn't be dissuaded by these recent stock slumps. They should, however, be choosy about which titles they pick for their portfolios, as there is wide disparity in business strategy, potential, and management talent. Investors should also be cautioned that this remains a volatile industry, and its stocks can be volatile.