By Mackenzie Tatananni

Quantum stocks posted outsized gains this week as the technology took center stage during an annual celebration of industry progress. And while IonQ saw its best performance in more than a year, two newcomers fared even better.

World Quantum Day on April 14 saw a flurry of announcements from a growing roster of public quantum firms. Among the most significant was an announcement from College Park, Md.-based IonQ, which said its researchers had connected two physically separate quantum systems, paving the way for future networks.

It has been a stellar week for the stock market overall. Investors can't write off the contributions of easing tensions in the Middle East. But quantum stocks were standouts.

Through Thursday's close -- before the Strait of Hormuz was declared open to commercial traffic -- the S&P 500 had gained 3.3% week to date. Quantum pure-plays had a strong run over the same period.

IonQ and D-Wave Quantum each gained more than 50% this week, while Rigetti Computing advanced 33%. The gains marked IonQ's best stretch since the week ending Nov. 8, 2024, according to Dow Jones Market Data.

Recent entrants into the public market also surged. Infleqtion, the maker of quantum sensors and neutral atom computers, gained nearly 24%. The company said last week that it had deployed updated hardware to the International Space Station alongside NASA. Then, on Tuesday, Infleqtion was name-dropped by Nvidia at a virtual conference.

It seems these developments were enough to convince Citi Research to initiate coverage on the shares Tuesday, rating them at Buy with a $20 price target. Analysts noted Infleqtion was among the partners already using Nvidia's Ising platform, which got its own nod at the conference.

By far the largest gainer this week was Xanadu Quantum Technologies, shares of which nearly quadrupled. Xanadu has only been public since the end of March, making the shares' first few weeks on the Nasdaq a whirlwind.

This week was Xanadu's best so far, as was the case for Horizon Quantum Holdings, which also went public through a SPAC merger last month. The Singapore-based company specializes in quantum software, a focus that lends itself to partnerships with quantum hardware developers.

Horizon's name was thrust into the news this week as the company announced a string of partnerships. Shares surged more than 20% on Wednesday after the company unveiled a collaboration with a European quantum computing hardware company, Alpine Quantum Technologies.

Perhaps most pivotal was Horizon's strategic agreement with IonQ to acquire one of the developer's 256-qubit quantum computers. Through that partnership, Horizon now has linked itself to one of the most-watched pure plays in the industry.

Quantum fans shouldn't get too comfortable. The return of market volatility or a technological setback could immediately send the stocks into a tailspin. However, for many investors betting on quantum's long-term potential, this week was a chance to take a breather. Time will tell where the industry goes next.

Write to Mackenzie Tatananni at mackenzie.tatananni@barrons.com

This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.

(END) Dow Jones Newswires

April 17, 2026 15:50 ET (19:50 GMT)

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