Retail traders from Reddit’s WallStreetBets flocked to uranium-mining companies on September 13 amid a price rally in the radioactive material, as investors bet that the nuclear fuel would become a central tool in the decarbonization of the world’s energy systems.

In Australia, Sydney-listed uranium miners Peninsula Energy, Energy Resources of Australia, and Bannerman Energy jumped by 40% over the past several days. In London, miner Aura Energy jumped more than 75% and Yellow Cake, a company that acts as an exchange-traded fund for uranium, rose 15%. Over in New York, uranium futures have been at their highest level in seven years, surging 40% over the past month to $42.40.

And in Asia, shares in Japanese utilities TEPCO, Kansai, and Shikoku Electric Power rose sharply after Fumio Kishida, the leading contender to become the country’s next prime minister, U-turned on his position on nuclear power and noted the energy source would be necessary to achieve the country’s net-zero goals.

The stocks largely stayed level or continued their rise into September 14, offering little sign that the rally had reached its end—or even its half-life.

The rally of shares in uranium miners follows on the heels of a buying spree by Sprott Physical Uranium Trust—a Toronto-listed fund that gives investors direct exposure to the metal—which bought some 850,000 pounds of the nuclear fuel last week and 1.4 million pounds the week before.

The trust has amassed around 25 million pounds of the metal since its launch in July, a big slice if one considers the total mined supply of uranium in 2019 was only around 120 million pounds, according to the World Nuclear Association.

Interest in nuclear energy and uranium as tools for decarbonizing the energy system has been growing for some time. Nuclear power can provide reliable, low-cost, low-carbon energy, and many countries are considering it as a baseload energy source to be used to fill the gaps of intermittent renewables and replace fossil fuels.

This wager on future energy systems in part pushed forward the rally by r/WallStreetBets, which is home to the same retail traders behind the rise of meme-stock GameStop. Prior to the stock rise in uranium, commenters on the forum were drawing parallels between the video game retailer and uranium.

One of the world’s largest publicly traded uranium companies, Canada’s Cameco Corp., which also rose 12% over September 13 and September 14, is the second most talked about company on Reddit, according to SwaggyStocks, a website tracking the mentions of ticker symbols.

“It is not a secret that investors’ newfound interest in uranium, predominantly through Sprott’s physical uranium trust, is the driving force behind its resurgence,” Morgan Stanley strategists Marius van Straaten and Susan Bates wrote in an investor note.

The analysts said that, moving forward, investors will cast a critical eye on the sustainability of the rally, as the baseline supply and demand fundamentals of uranium haven’t changed since Sprott’s buying spree. “While coal and natural gas prices are driven up by actual market tightness, uranium’s underlying supply-demand fundamentals haven’t meaningfully changed over the last few months to warrant this price surge,” Morgan Stanley’s analysts noted.

To further the discussion of all things related to uranium investment, a new subreddit named r/UraniumSqueeze—dedicated to investors and traders “passionate about the uranium market”—was created in February and has attracted 14,000 members. It lauds itself as a stricter forum than r/WallStreetBets, claiming it will not allow any memes in order to maintain its integrity as a serious place to discuss uranium investing.

But r/WallStreetBets is still having fun with it.