Polestar's stock fell 29% last week.
The drop followed a steep run-up in the last hour of trading the week before.
There was no news driving either move.
Shares of electric vehicle maker Polestar (NASDAQ: PSNY) had a rough week, even by the volatile standards of electric vehicle stocks. A rapid sell-off left Polestar's American depositary shares down 29.2% for the week by Friday's close.
What drove that decline? The answer isn't obvious, but here's what we know.
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There was no news driving this move. (I covered this company when I was a reporter. If there were news, I'd know about it, and I'd share it with you.)

PSNY data by YCharts.
But here's what I do know: Someone, for some reason, bought a ton of Polestar stock in the last hour before U.S. markets closed on Friday, Feb. 27. Those purchases drove the stock price up from $18.71 at 3 p.m. ET to $23.38 at closing just an hour later. That's a gain of almost exactly 20% in just an hour of trading.
Image source: Polestar.
Was it a fund trading a rumor? A glitch in an algorithm? A trader's mistake? Something else?
Whatever it was, it was unwound pretty quickly. While the stock stayed up in that range on the following Monday, the share price fell below $20 in early trading on Tuesday and spent the rest of the week bouncing around the teens.
Here's a six-month chart for some more context.

PSNY data by YCharts.
We can see that the stock sold off after Polestar reported its third-quarter results on Nov. 12 -- and again after a reverse stock split took effect in December. But there was no news driving the most recent sell-off.
The takeaway here is that Polestar's recent price gyrations aren't driven by its fundamentals. Shareholders may need to hold tight at least until Polestar reports its full-year 2025 results later this month.
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John Rosevear has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.