What happened

After less than a month on the public markets, the Israeli start-up X-ray machine maker Nano-X Imaging (NASDAQ:NNOX) has more than doubled off its $18 offer price. Shares shot up more than 15% in early trading Tuesday and were still up about 7.7% at 1:50 p.m. EDT.

So what

Nano-X was rising in a market where the rest of the Nasdaq is down more than 2% despite there being no particular news of note. Nor has Nano-X said anything market-moving itself today.

I suspect investors are just still enthused by the rapid rise of this medical technology stock, and its disruptive business model. It is promising to build X-ray machines for $10,000 and then give them away, making money instead by charging for use of the machines.

Cartoon professor with a pointer explains why a stock arrow is rising

Image source: Getty Images.

Now what

In a business where X-ray machines ordinarily cost upward of $2 million, Nano-X's promise to give the machines away is certain to attract interest, even as its pay-per-use business model (the latest example of selling hardware as a service) promises to generate recurring revenue streams far into the future.

In the meantime, Nano-X remains a money-losing start-up with literally no revenue to speak of. It's an extremely speculative stock, albeit one that is rewarding its speculators richly today.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.