Stock Market Today, Sept. 23: IonQ Surges on Quantum Breakthrough and Nvidia Partnership

ExpandNYSE: IONQIonQPremium FeatureMoneyball Superscore63/100Today's Change(4.42%) $1.80Current Price$42.54Key Data PointsMarket Cap$17BMarket cap calculated using publicly traded shares outstanding only. Does not include unlisted, private, or dual-class non-traded shares. Implied market cap may vary.Day's Range$41.63 - $46.0552wk Range$25.89 - $84.64Volume72.3MAvg Vol20.3MGross Margin-3317.96%IonQ (IONQ +4.42%), a full-stack trapped-ion quantum computing provider, closed at $42.54, up 4.42%. It rose after a real-time error-correction breakthrough and a research-center collaboration with Nvidia (NVDA -1.47%). Trading volume reached 69.9 million shares, coming in about 233% above its three-month average of 21.0 million shares. IonQ IPO'd in 2021 and has grown 294% since going public.How the markets moved todayThe S&P 500 (^GSPC -0.75%) fell 0.75% to 7,706, and the Nasdaq Composite (^IXIC -1.13%) fell 1.13% to 26,936. Among quantum computing hardware, software, and cloud-access services peers, Rigetti Computing (RGTI -3.12%) closed at $16.00, down 3.12%, and D-Wave Quantum (QBTS -4.27%) closed at $16.81, down 4.27%, as the group tracked IonQ's decoder news.What this means for investorsIonQ defied a tech downturn today on company-specific news, prompting investors to bet that its quantum computing developments signal a leadership position in the space. The company announced a breakthrough in error decoding with what it called "the industry's first end-to-end real-time quantum error correction decoder that runs on a single standard off-the-shelf central processing unit (CPU)."In addition to that news, IonQ announced a potentially important step toward commercializing its quantum systems. Its Superion 256 system will be installed in Nvidia's accelerated quantum research center to run as a niche processing system alongside Nvidia GPU (graphics processing unit) clusters.That could lead to hybrid developments and create large-scale systems for AI use cases that include both GPU and quantum designs. That has investors feeling more confident about IonQ's future commercial success.Read NextSep 23, 2026 •By Adria CiminoBetter Quantum Computing Stock: IonQ vs. RigettiSep 22, 2026 •By Micah Zimmerman2 Magnificent Quantum Computing Stocks to Buy and Hold for 10 YearsSep 22, 2026 •By Leo SunWhere Will IonQ Stock Be in 5 Years?Sep 22, 2026 •By Sean WilliamsIonQ, Rigetti Computing, D-Wave Quantum, and Quantum Computing Inc.

Are Sending Shockwaves Through Wall Street With This $895 Million WarningSep 22, 2026 •By Keithen DruryIonQ Just Raised 2026 Revenue Guidance.

This Quantum Computing Pure-Play Looks Like a Brilliant Buy Now.Sep 21, 2026 •By Adam SpataccoMeet the Quantum Computing Stock Growing Faster Than NvidiaAbout the AuthorHoward Smith is a contributing Motley Fool stock market analyst covering technology and industrial stocks. Prior to The Motley Fool, Howard spent nearly 30 years supervising quality and operations in the steel industry, mostly with leading steel company Nucor. He holds a bachelor’s degree in metallurgical engineering from Lafayette College and a master’s degree in environmental engineering from Johns Hopkins University.TMFBuilt2LastStocks MentionedIonQNYSE: IONQ$42.54(+4.42%)+$1.80Motley Fool Stock Advisor’s Latest PickGet Access---% Avg Return*Average returns of all recommendations since inception. Cost basis and return based on previous market day close.