NEW YORK, NY – September 5, 2026 (STL.News) The U.S. stock market has produced some extraordinary winners in 2026, with artificial intelligence, memory chips, data-center infrastructure and biotechnology driving several major stocks dramatically higher.
Through the market close on Friday, September 4, the five best-performing stocks in the S&P 500 this year are SanDisk Corp. (NASDAQ: SNDK), Moderna Inc. (NASDAQ: MRNA), Dell Technologies Inc. (NYSE: DELL), Micron Technology Inc. (NASDAQ: MU) and Seagate Technology Holdings plc (NASDAQ: STX).
The gains are remarkable. All five stocks have risen more than 180% since the beginning of the year, while SanDisk has increased more than 500%.
Unlike rankings that include thinly traded microcap companies, this list focuses on S&P 500 companies, giving investors a clearer picture of the major publicly traded businesses delivering the strongest returns in 2026.
Top Five Best-Performing Stocks in 2026 – S&P 500 Stocks of 2026
| Rank | Company | Ticker | 2026 YTD Return* |
|---|---|---|---|
| 1 | SanDisk Corp. | SNDK | +536.38% |
| 2 | Moderna Inc. | MRNA | +399.06% |
| 3 | Dell Technologies | DELL | +305.85% |
| 4 | Micron Technology | MU | +224.84% |
| 5 | Seagate Technology | STX | +183.92% |
*Returns are based on market-price data covering January 1 through the September 4, 2026 close. Different financial-data providers may report slightly different percentages depending on methodology, dividends and starting prices.
The list reveals one of the most important stories on Wall Street this year: AI is no longer primarily a semiconductor-processor story.
Three of the five leaders — SanDisk, Micron and Seagate — are directly connected to memory and data storage. Dell is benefiting from massive demand for AI servers and computing infrastructure.
Moderna is the exception, with biotechnology developments propelling its shares higher.
No. 1 SanDisk — Up 536%
SanDisk has been the standout S&P 500 stock of 2026.
Shares have gained about 536% through September 4, meaning a hypothetical $10,000 investment that captured the full price increase would have grown to about $63,600 before considering taxes, trading costs, or other factors.
The rally has been backed by an extraordinary improvement in SanDisk’s business.
For fiscal 2026, SanDisk reported revenue of approximately $20.25 billion, an increase of 175% from the previous year. The company’s data-center revenue jumped 437% to approximately $5.15 billion.
The numbers became even more dramatic during its fiscal fourth quarter.
Revenue reached approximately $8.97 billion, increasing 372% from $1.90 billion during the comparable quarter a year earlier. SanDisk said about one-third of its sequential revenue growth came from higher volume and approximately two-thirds from higher pricing.
AI data centers are an important part of the story.
Training and operating increasingly sophisticated artificial-intelligence systems requires enormous amounts of memory and storage. SanDisk specializes in NAND flash technology and storage products used across data centers, edge computing and consumer applications.
The company has also been moving toward longer-term customer agreements. Reuters reported in August that SanDisk had agreements with six customers worth at least $93.9 billion, with an increasing portion of production expected to be covered by longer-term arrangements.
SanDisk wasn’t finished Friday.
Shares surged approximately 12% on September 4, making SNDK the S&P 500’s biggest gainer that day as memory and AI-related stocks rallied.
No. 2 Moderna — Up 399%
The second-biggest winner presents an entirely different story.
Moderna shares have gained about 399% in 2026, an extraordinary reversal for a company that spent years trying to convince investors its mRNA technology could build a major business beyond COVID-19 vaccines.
A major catalyst arrived in August.
Moderna shares more than doubled during the August 19 session after the company released encouraging late-stage results involving its personalized mRNA cancer therapy developed with Merck.
The treatment, intismeran, combined with Merck’s Keytruda, reduced the risk of recurrence and spread in a late-stage trial. The news added roughly $30 billion to Moderna’s market value during the session, Reuters reported.
The development matters because Moderna has been trying to show that its mRNA platform has applications well beyond infectious-disease vaccines.
Investors should nevertheless recognize the difference between Moderna and the technology companies dominating the rest of the list.
Moderna remains a biotechnology company with substantial clinical, regulatory and commercialization risks. Its second-quarter results showed only about $100 million in revenue and a GAAP net loss of roughly $800 million.
That makes Moderna’s enormous stock appreciation largely a reflection of dramatically higher expectations for its pipeline rather than simply growth in current earnings.
No. 3 Dell Technologies — Up 306%
Dell may be one of the clearest examples of how AI spending has expanded beyond GPU manufacturers.
Dell shares have gained about 306% through Friday’s close.
The company is selling the infrastructure required to deploy artificial intelligence at enormous scale.
Dell recently raised its annual revenue forecast to about $192 billion from $167 billion and its adjusted earnings-per-share forecast to $25.50 from $17.90.
The reason is extraordinary demand for AI servers.
Dell has booked more than $130 billion of AI-server orders over the past 12 months, according to company executives cited by Reuters. The company now expects fiscal 2027 revenue from AI-optimized servers to reach approximately $74 billion.
Second-quarter revenue rose 58% to a record $47 billion, while the Dell business, which includes servers, storage and software, posted an 89% revenue increase.
Those numbers demonstrate how enormous the AI infrastructure buildout has become.
The beneficiaries aren’t limited to Nvidia and other chip designers. Servers need processors, memory, networking equipment, storage, cooling, power infrastructure, and physical data-center capacity.
Dell sits near the center of that spending cycle.
No. 4 Micron Technology — Up 225%
Micron Technology has been another enormous beneficiary of the AI infrastructure boom.
MU has gained about 225% through September 4, according to the S&P 500 performance ranking.
Micron’s financial results explain investors’ enthusiasm.
In its fiscal third quarter, the company reported $41.46 billion in revenue, up from $23.86 billion in the preceding quarter and $9.30 billion in the same quarter a year earlier.
GAAP net income reached approximately $28.24 billion.
One of the company’s most important products is high-bandwidth memory, commonly called HBM.
HBM has become critical to advanced AI computing because the enormous processors powering artificial-intelligence systems need rapid access to huge amounts of data.
Demand has become so strong that Micron reportedly plans to expand HBM production capacity substantially. MarketWatch reported Friday that demand for HBM is already more than twice current supply and continues to grow rapidly.
Micron gained another 6.1% Friday, underscoring continued investor enthusiasm for the memory sector.
No. 5 Seagate Technology — Up 184%
Seagate rounds out the top five with a year-to-date gain of approximately 184%.
The company provides another example of an older technology business finding itself at the center of the AI revolution.
AI generates tremendous quantities of data, and that information needs to be stored.
Seagate’s fiscal 2026 revenue reached approximately $12.2 billion, increasing 34% from fiscal 2025. The company generated $3.1 billion in free cash flow and reported GAAP net income of approximately $3.18 billion, more than double the previous year’s level.
Fourth-quarter revenue reached $3.63 billion, compared with $2.44 billion a year earlier.
Seagate CEO Dave Mosley attributed the company’s performance to strong cloud data-center demand and said AI’s acceleration of data generation should support long-term demand for mass-capacity storage.
Like SanDisk and Micron, Seagate participated in Friday’s memory and storage rally, gaining roughly 6%.
AI Dominates the 2026 Winners
The composition of the top-five list may be more significant than the individual rankings.
Four of the five companies are tied directly to the massive infrastructure investment surrounding artificial intelligence.
SanDisk supplies flash storage.
Micron supplies advanced memory.
Seagate supplies mass-capacity storage.
Dell builds servers and infrastructure.
That suggests the AI investment theme has broadened considerably. Investors aren’t only rewarding the companies designing the processors at the center of AI systems. Capital has moved into businesses supplying the memory, storage and physical computing infrastructure needed to run them.
Friday’s trading reinforced that trend. SanDisk climbed about 12%, while Seagate, Western Digital and Micron each gained roughly 6%. The PHLX Semiconductor Sector Index advanced more than 3% even as the broader S&P 500 declined.
What Investors Should Watch Next
Extraordinary gains don’t guarantee extraordinary future returns.
In fact, rapid appreciation can increase risk because investors may begin pricing years of future growth into today’s stock price.
Memory and storage are historically cyclical industries. Today’s shortages and strong pricing can eventually encourage additional production, potentially creating excess supply later.
Biotechnology carries a different set of risks. Moderna’s future valuation depends heavily on clinical trials, regulatory approvals and the eventual commercial success of products still moving through development.
AI infrastructure companies face their own question: how long can the current capital-spending boom continue at its present pace?
Those issues will help determine whether the five stocks leading the S&P 500 through the first eight months of 2026 remain leaders through the end of December.
For now, however, the numbers are decisive.
SanDisk, Moderna, Dell Technologies, Micron Technology and Seagate Technology are the five best-performing S&P 500 stocks of 2026 through the September 4 close, and four of them tell essentially the same broader story.
Wall Street’s AI boom has moved beyond artificial-intelligence processors. Increasingly, investors are betting on the companies that store the data, supply the memory and build the machines that make AI possible.
Disclaimer: This article is provided for news and informational purposes only and does not constitute investment advice, a recommendation to buy or sell securities, or financial planning advice. Stock prices can decline substantially, and past performance does not guarantee future results.
