Stellantis (STLAM) Stock Plunges 43% in 2026 as Solid-State Battery Testing Begins

Key Takeaways

• Stellantis maintains a 9.5% ownership position in Factorial Energy, a solid-state battery developer based in the United States, with the stake valued at approximately $126 million
• The investment, distributed between Stellantis Ventures and Stellantis Europe, represents about 8.67 million shares in the startup
• Laboratory testing of Factorial’s battery technology demonstrated 375 Wh/kg energy density with charging times of approximately 18 minutes from 15% to 80%
• Real-world road testing has commenced using Factorial’s FEST battery cells installed in a prototype Dodge Charger Daytona vehicle
• Shares of STLAM have plummeted almost 43% year-to-date in 2026, with a recent 3.7% decline following negative news from BMW

An SEC disclosure has revealed that Stellantis maintains a 9.5% ownership stake in Factorial Energy, with the position currently worth approximately $126 million based on present valuations. The investment is distributed across both Stellantis Europe and Stellantis Ventures entities.

Stellantis N.V., STLA

The automaker’s initial capital commitment to Factorial dates back to 2021, when Stellantis injected €75 million (approximately $86 million) into the battery technology company. This financial commitment has now transformed into an equity stake, positioning the automotive giant as a significant stakeholder in the emerging technology.

Jon Nelson, who leads Stellantis Financial Services as CEO, has secured a board seat at Factorial, transforming what began as a purely financial transaction into a strategic operational partnership.

The regulatory filing further indicated that Stellantis remains open to expanding its investment in Factorial, characterizing the company as representing a “compelling investment opportunity.”

Factorial has recently launched road testing of its solid-state battery technology in a development version of the Dodge Charger Daytona. This milestone represents the technology’s first deployment in actual driving scenarios beyond controlled laboratory settings.

During lab evaluations, Factorial’s battery cells achieved an energy density measurement of 375 Wh/kg. The cells also demonstrated the capability to charge from 15% to 80% capacity in about 18 minutes — performance metrics that would constitute a significant advancement over existing lithium-ion battery technology if achievable at commercial scale.

Solid-state battery technology offers reduced weight compared to traditional lithium-ion battery packs while promising enhanced driving range, accelerated charging capabilities, superior safety characteristics, and potentially reduced lifecycle costs. The primary obstacle remains manufacturing scalability, a challenge the automotive sector has yet to overcome.

Strategic Rationale Behind Stellantis’ Investment

For Stellantis, the partnership with Factorial represents a component of its comprehensive strategy to maintain competitive positioning in the electric vehicle technology landscape. Industry experts widely regard solid-state batteries as the next transformative advancement in energy storage, making early strategic alliances potentially critical when the technology reaches commercial viability.

The automaker’s approach prioritizes strategic involvement with a promising technology developer rather than attempting full ownership, particularly given Factorial’s demonstrated laboratory achievements and progression toward practical validation.

Share Price Challenges

While the Factorial development offers positive technological prospects for investors to consider, Stellantis shares have experienced significant headwinds throughout 2026. STLAM has declined nearly 43% since the beginning of January.

The latest downturn occurred this week, with shares dropping 3.7%. This decline coincided with a profit warning issued by BMW, which triggered broader selloffs across European automotive stocks.

Stellantis continues to face challenging conditions across its primary geographic markets, with the BMW announcement intensifying existing sector-wide pressures.

The SEC documentation, which officially discloses the Factorial ownership position, was filed on June 19, 2026.