McLaren Racing CEO Zak Brown sent a formal letter to FIA President Mohammed Ben Sulayem last week calling for immediate clarification of Formula 1's multi-team ownership rules, according to three people familiar with the correspondence. The timing is pointed: Mercedes have held preliminary discussions with Renault about a minority stake in the Alpine F1 operation, while Red Bull's Christian Horner has privately explored equity participation in the same team through separate channels.

Brown's letter does not propose an outright ban. It requests the FIA codify explicit ownership thresholds and impose stricter firewall requirements between teams sharing common investors. Current rules prohibit a single entity from holding a "material stake" in more than one constructor, but material remains undefined. Teams have interpreted it as anything above 5%, while the FIA has declined to publish a binding figure. Brown is asking for 3% as the hard cap, with mandatory disclosure of any holding above 1%, per two people who reviewed the draft. The letter runs four pages and includes three historical precedents where ambiguous ownership created competitive distortions, including the Toro Rosso-Red Bull arrangement that predates Liberty Media's 2017 acquisition.

The structural pressure is franchise valuation. Andretti's failed entry bid saw private valuations of the eleventh team slot reach $850 million before the FIA and Formula One Management declined the application in January. Existing teams now trade privately at $2.1 billion to $2.8 billion depending on recent results, per three family-office allocators approached by mid-tier constructors in the past nine months. Sovereign wealth funds from the Gulf have approached at least four teams since Abu Dhabi in December. One team principal described the inbound interest as "every call starts with 'we like the Concorde economics, what's your number.'" The Concorde Agreement guarantees each constructor a share of roughly $70 million annually in baseline payments before performance bonuses, and that floor creates debt-like predictability for financial engineers.

Mercedes' interest in Alpine is defensive. Renault's board has debated full withdrawal from Formula 1 three times since 2022, according to two Renault Sport executives. A minority stake from Mercedes would stabilize the operation, preserve Renault's engine supply contract through 2026, and give Mercedes optionality if Toto Wolff ever exits the Brackley works team. Horner's involvement is personal and separate from Red Bull: he has discussed a sub-5% stake with Luca de Meo, Renault's CEO, and positioned it as advisory rather than operational, per one person close to those talks. Horner's calculus is succession; if he leaves Red Bull in the next 24 months, Alpine is the logical next chair, and a small equity position creates alignment without triggering FIA conflict-of-interest protocols.

Brown's letter also names the Disney problem, though not explicitly. Disney Consumer Products announced an expanded Formula 1 partnership this week covering F1 Academy, the junior women's series. Disney already holds F1 broadcast rights in select Southeast Asian markets and sponsors two teams through ABC-branded activations. If Disney later sought a direct team stake—plausible given its sports betting and franchise strategy under Bob Iger—the current rules would allow up to 4.9% in multiple constructors without formal review. Brown's language in the letter describes this as "brand conglomerate creep" and argues that media companies with commercial leverage over the sport should face separate caps. One team principal who reviewed the letter noted Brown "basically wrote the IPO prospectus for why this matters to future buyers."

The FIA has six weeks to respond under its governance manual. Ben Sulayem has already signaled he wants the matter on the April World Motor Sport Council agenda in Bahrain, according to two federation sources. That meeting occurs three days after the season-opening race, which means team principals will negotiate the rule in the paddock while their cars are on track. One constructor CEO said, "Zak just moved this from the lawyers' room to the principal's meeting, and now we either get clarity or we get chaos."

Mercedes declined to comment on Alpine discussions. Renault's press office said "all ownership structures are regularly reviewed." Horner did not respond to messages. Brown's office confirmed the letter exists but declined to provide a copy. Three teams are now drafting their own position papers, expected to circulate before Bahrain. The ownership question also affects 2026 engine supplier negotiations, since teams want to know who will own their rivals before committing to long-term power unit contracts. Ferrari's Fred Vasseur told one sponsor last month that "the grid in 2027 might have different names on the same garages."

The forward signal is April 2. If the FIA punts, expect teams to leak draft term sheets and force Ben Sulayem into a mid-season ruling under pressure. If the FIA codifies a 3% cap, at least two current ownership discussions will require restructuring, and one sovereign fund will likely redirect capital toward a new entry bid rather than minority stakes. The Alpine situation will resolve first, because Renault's board meets in Paris on March 18 and de Meo needs a decision before the French government—holder of 15% of Renault shares—starts asking why the company is still spending €130 million annually on racing.