Some deals are so obvious they keep getting attempted, and so difficult they keep falling apart. The saga of Glencore (GLCNF) and Rio Tinto (RIO) is exactly that story, and it just happened again.

For more than a decade, billionaire Ivan Glasenberg has been chasing what you might call the white whale of mining M&A. As Glencore's former CEO and current largest shareholder, he's wanted to merge his company with Rio Tinto, creating what would be a mining superpower worth over $200 billion. For most of January, it looked like he might finally pull it off. The two companies were in their most serious talks yet, the fourth attempt in 20 years. Then, with a U.K. takeover deadline breathing down their necks, the whole thing imploded in 24 hours.

How It Unraveled

The latest round started quietly in mid-December when the companies entered formal discussions. Things heated up in January once word leaked out, triggering U.K. takeover rules that gave Rio until February 5 to either make a formal offer or walk away. By that point, advisers had spent weeks crawling through Glencore's operations, and both sides thought this was finally it.

But on deadline day, they hit the same wall they always do: valuation. Glencore wanted its shareholders to own about 40% of the combined company, a figure that reflected its view of its copper assets and trading business. Rio's executives weren't buying it. They concluded the gap was unbridgeable and issued a statement saying they "could not reach an agreement that would deliver value to its shareholders."

Under U.K. rules, they can't talk again for six months unless a third party gets involved or Glencore formally asks to reopen discussions.

Why This Deal Makes So Much Sense

Here's the thing: on paper, this merger is blindingly obvious. Rio Tinto is dangerously overexposed to iron ore, a market facing oversupply, falling prices, and total dependence on Chinese demand. The company is also stuck with a 14.5% stake held by China's state-owned Aluminium Corp, a shareholding that limits buybacks and strategic flexibility.

Meanwhile, Glencore has watched its copper output collapse by more than 40% over the past decade. Now it's betting big on a massive greenfield project in Argentina, exactly the kind of capital-intensive, high-risk venture that Glasenberg himself spent years warning against.

A merger would solve both problems elegantly. Rio would instantly become the world's top copper producer with a million tons of future growth, gaining exposure to the metal powering the electrification era. Glencore would diversify away from coal, tap into Rio's operational discipline, and benefit from a stronger balance sheet.

The strategic logic is so compelling that every Rio CEO since Tom Albanese has supported it. The race for copper assets has intensified recently as rivals pursue large acquisitions, adding urgency to the talks. Neither company wants to be left behind.

Same Problems, Different Year

But the same obstacles keep resurfacing: valuation, governance, and culture. This time, Glencore showed flexibility by agreeing to let Rio take both the CEO and chairman roles. In return, it wanted a share-exchange ratio giving its investors roughly 40% of the combined company.

Rio's advisers tied their valuation to share prices on the day the deal went public. Glencore saw that as arbitrary and a material undervaluation of its copper portfolio. Neither side blinked, and the talks died.

Now both companies face, alone, the exact problems they hoped to solve together. As Bloomberg columnist Javier Blas noted in his analysis, there are no winners here. Rio is stuck with an expensive lithium diversification that isn't delivering and a Chinese state shareholder it can't shake. Glencore remains overexposed to coal, a market temporarily propped up by Indonesian production cuts but facing long-term structural decline. It's also staring down a hefty bill for that risky Argentine copper mine, and it has a concentrated shareholder structure with Glasenberg and a Qatari sovereign wealth fund holding nearly 20% of the company.

Will They Try Again?

Both sides are publicly dismissive about trying again, but let's be realistic. Time heals wounds, egos soften, and the underlying problems aren't going anywhere. The strategic logic that made sense last month will still make sense in six months or six years.

There's one wrinkle, though. Glasenberg is now 69. Despite being a former Olympic-caliber athlete, even he must be thinking about how many more runs at this he has left. The white whale has gotten away four times now. The question is whether there's time for a fifth harpoon.

RIO Price Action: Rio Tinto shares were up 1.85% at $92.81 during premarket trading on Friday.