Shares of D-Wave Quantum (QBTS -9.67%) took a tumble on Thursday, falling as much as 11.5% by 12:50 p.m. ET. The company didn’t do anything wrong today — investors simply took some profits off the table after a string of price surges. After all, D-Wave closed Wednesday’s trading session at an all-time high, having gained 4,390% in the previous 52 weeks.

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Why D-Wave has been on such a tear lately

D-Wave has gone from strength to strength recently, business-wise. Its quantum computing peers presented large capital investments and significant technology advances in September, driving the whole quantum industry higher last month.

On top of that surge, D-Wave won an innovation award from Fast Company this week, swiftly followed by a large system sale to a European quantum research veteran named Swiss Quantum Technology SA. Both events pushed D-Wave’s stock even higher. It’s no surprise to see some profit-taking at this lofty plateau, on a fairly quiet day.

The sky-high price tag is giving me vertigo

The profit conversion moves make even more sense when you put D-Wave’s soaring stock in context. Despite the rash of good news, this company is deeply unprofitable and its stock trades at 628 times trailing sales today. It makes market darlings like Palantir Technologies and Nvidia look affordable at 122 and 27 times sales, respectively.

I thought D-Wave looked incredibly expensive six months ago, and the stock has gained 533% since then. The quantum computing euphoria looks a bit mistimed, as none of the leading industry experts are likely to make money in the next several years.

So if you’re a D-Wave stock owner who isn’t selling these days, I can only applaud your fortitude from Wall Street’s sidelines. And I’m still not buying your shares, since the unsustainable valuation seems destined for a sharp correction.