If Starbucks bought Chipotle Mexican Grill — a scenario the Financial Times reported this week was being explored by the coffee giant — it would be the largest purchase of one restaurant chain by another ever recorded in the United States. It would also almost certainly rank among the biggest missteps, given the limited synergies between the two brands, the sheer size of the deal, and the potential distraction it would create while Starbucks leadership works through its turnaround.

Chipotle investors initially cheered the report, with shares rising as much as 8% on Thursday after it was published. The stock has since fallen back to roughly where it stood before the article appeared.

The enthusiasm is easy to understand. Starbucks CEO Brian Niccol is the star executive who knows Chipotle intimately after spending six years leading the burrito chain and orchestrating its turnaround before leaving in 2024 to fix Starbucks. On his watch, Niccol guided Chipotle out of the E. coli contamination crisis that had hammered sales in 2015 and 2016, improved its restaurants and operations, built a leading app, and ultimately helped the company double annual sales to $10 billion. More recently, however, Chipotle has struggled, and its shares have fallen by nearly half since his successor, Scott Boatwright, took the reins almost two years ago. (Chipotle did not respond to a request for comment.)

Starbucks investors reacted rather differently, sending shares lower on fears that a transaction of this scale would prove a major distraction — even for a CEO as highly regarded as Niccol, who is credited with pulling Starbucks out of a long slump through his "Back to Starbucks" turnaround plan, restoring growth, and winning back the goodwill of its customers.

"Starbucks is still executing its turnaround strategy, and acquiring Chipotle could consume significant senior management time on financing, integration, organizational design, systems, and personnel," BTIG analyst Pete Saleh wrote in a note. Starbucks itself told Fortune in a statement that it was "laser focused" on that turnaround.

The fact that shares in both companies have essentially returned to their levels before the article suggests the stock market has concluded the deal is unlikely to happen. Absent a formal offer or a clearer signal from either board, the storyline to watch now is whether the turnaround itself keeps showing up in Starbucks' results.

Chipotle's market capitalization is about $40 billion, meaning Starbucks would likely have to offer roughly $50 billion — half of Starbucks' current valuation — once the standard 20% acquisition premium is applied. For scale, the biggest recent restaurant-sector deals — among them Inspire Brands' roughly $11 billion takeover of Dunkin' Brands in 2020 — would come in at less than a quarter of that price. That enormous sum would in turn require Starbucks to borrow tens of billions of dollars, with interest expense damaging its profitability and potentially diverting money away from the investments it is making to upgrade its coffee shops. Investors are already watching Starbucks' capital spending closely, given how pricey café makeovers and store equipment to improve service can be, and how heavily they eat into profit margins. The company could instead turn to equity, but that would carry undesirable effects and pressure the shares.

Ultimately, a Starbucks–Chipotle deal offers little to improve either company's performance. Wall Street firm William Blair estimated about $300 million in potential annual corporate and technology savings, to be sure, but that hardly justifies a $50 billion transaction. What's more, Starbucks is focused on beverages, and the food it does sell is largely premade, while Chipotle makes freshly prepared foods.

Many observers are concluding that the deal's initial appeal stemmed from the regard the market holds for Niccol as leader. "The clear anchor to why this would make any sense is management," Citi analyst Jon Tower wrote in a note.

But even someone as talented as Niccol can only do so much at once. Focus is core to delivering a turnaround. Indeed, some of Niccol's moves at Starbucks have involved eliminating complexity and distractions — most notably selling majority control of Starbucks' China business to Boyu Capital last year in a deal that valued the unit at roughly $4 billion.

Niccol has little experience integrating other brands or handling M&A. He was enormously successful at Taco Bell, then at Chipotle, and now at Starbucks by being relentlessly focused on restaurant operations and customer experience. And with this deal apparently unlikely to happen, he can continue to be.

This story was originally featured on Fortune.com.