The electric vehicle (EV) sector hasn't exactly been a favorite of investors so far this year, but you wouldn't know that from how EV and related stocks traded on Monday. While they didn't exactly skyrocket in price, many enjoyed palpable gains on the day to enrich their investors slightly.

Next-generation power pack developer Freyr Battery (FREY) was one of them, closing the day an even 10% higher. Rising at nearly a similar percentage rate was rare earth materials specialist MP Materials (MP -2.26%), while Chinese EV manufacturer Li Auto (LI 0.67%) booked an almost 5% gain.

Hailing the latest development in the world of EVs

The trend-bucking incident occurred late Friday afternoon, with a post on X (formerly Twitter) composed of an extremely short sentence. Tesla CEO Elon Musk wrote in a post on his feed that the company would "unveil" a robotaxi this coming Aug. 8.

Musk is, almost unquestionably, the single-most influential figure in the EV world, so his pronouncements -- no matter how offbeat -- can carry a great deal of weight. This particular one excited investors, as Tesla's apparent dive into the robotaxi segment will immediately make it an important one throughout the EV world.

If they're not already developing EVs specifically designed for robotaxi functions, manufacturers like Li Auto will be expected to do so (and likely rewarded by shareholders for the move). And, of course, current and potential suppliers to the industry will be more attractive sideways plays on EV growth with this emergence.

Tesla isn't, of course, the only EV and EV-adjacent company realizing ambitious robotaxi plans.

Chinese ridesharing incumbent Didi Global (DIDI 0.22%) on Monday revealed that Andi, the joint venture it operates with EV manufacturer GAC Aion, earned a business license in that country. This makes Andi the only business in the sprawling Asian nation that can legally mass-produce autonomous robotaxis. Assuming they can get such products to market relatively quickly, both Didi and the joint venture stand to benefit very handsomely.

Robotaxis might be higher-margin products

The market players driving these stocks higher on Monday might be counting on the profit margins for robotaxis to be higher. In what might not be a coincidence, Musk's announcement coincides with media reports that Tesla is abandoning plans to manufacture a relatively low-priced car that industry observers have dubbed the Model 2. That car would have sold for around $25,000, certain market-watchers believe.