Here's a sentence that sounds impossible: Nvidia, the most valuable company in the world, is now cheaper than Coca-Cola.

That claim comes from The Motley Fool, and it hinges on a specific yardstick. "Cheaper" here doesn't mean the sticker price of a single share. It refers to the price-to-earnings ratio, or P/E — what The Motley Fool describes as the measure investors lean on most when they're paying for future profits.

A P/E ratio compares a company's stock price to how much money it actually earns. A lower ratio suggests investors are paying less for each dollar of profit. According to the reporting, Nvidia (NASDAQ: NVDA) now carries a lower P/E than Coca-Cola (NYSE: KO) — meaning that by this common valuation gauge, the chipmaker looks less expensive than the soft-drink giant.

The reason isn't that Nvidia's stock has collapsed. It's that Nvidia's earnings have grown so fast, driven by demand for its chips, that profits have caught up with — and outrun — its rising share price. When earnings climb faster than the stock, the P/E ratio falls, even for a company whose overall market value leads the world.

Coca-Cola, by contrast, is a slow-and-steady business whose profits grow modestly, so its valuation multiple has held relatively firm.

The comparison is striking precisely because the two companies are so different: one a booming semiconductor leader, the other a century-old consumer staple.

Why it matters: the headline is a vivid reminder that a stock's "price" and its "value" are not the same thing, and that surging profits can make even the market's biggest company look like a relative bargain.