S&P 500: The Winners and Losers of January 2026
After a strong 2025, when the S&P 500 gained about 16.5%, the index started 2026 on a much quieter note. The S&P 500 rose 1.34% in January, delivering a modest but positive opening to the year.
Beneath the surface, performance varied widely across individual stocks. While the majority of S&P 500 constituents finished January higher, only 182 stocks closed the month in negative territory. A handful of names posted outsized gains on earnings surprises, corporate updates, or major product and clinical milestones, while others saw sharp declines driven by valuation resets, regulatory headlines, or company-specific setbacks.
Some stocks clearly stood out at both ends of the spectrum. In this article, we review the best- and worst-performing S&P 500 stocks of the opening month of 2026 and break down the key reasons behind those price movements.
Top S&P 500 Performers of January 2026
Among the top performers were SanDisk Corp., Moderna, and Seagate Technology. Each posted enormous gains, supported by clear company-specific catalysts ranging from surging demand to major clinical and product milestones.
SanDisk Corp. ($SNDK) +142.75%
Flash memory maker SanDisk was the S&P 500’s standout winner in January, more than doubling its stock price. Shares extended an already record run after blowout quarterly results and guidance highlighted unprecedented demand for its storage products.
SanDisk’s fiscal second-quarter revenue jumped 61% year over year to about $3.03 billion, while net income surged 672% to $803 million as the company benefited from a global flash memory shortage. Management sharply raised its outlook, targeting next-quarter revenue of $4.4 billion to $4.8 billion versus roughly $3 billion consensus, prompting analysts to lift price targets.
Demand from AI data centers has been a major driver, as large technology companies continue to spend aggressively on storage to support AI model training, pushing flash memory prices to record levels. CEO David Goeckeler said the company’s products are playing a critical role in powering AI and global technology infrastructure.
SanDisk went public in 2025 following a spinoff and joined the S&P 500 late last year. By the end of January, shares were trading at all-time highs, reflecting strong investor enthusiasm around earnings momentum and its positioning in AI-related storage. The stock has also surged nearly 20x from last year’s lows of $27.89, underscoring the magnitude of the turnaround.
Moderna ($MRNA) +49.44%
Biotechnology company Moderna started 2026 with a strong rebound, rising nearly 50% in January after a major cancer vaccine update.
The rally was driven by five-year follow-up data from a Phase 2b melanoma trial of Moderna’s personalized mRNA cancer vaccine in combination with Merck’s Keytruda. The results showed that patients receiving the combination therapy had a 49% lower risk of cancer recurrence or death compared with Keytruda alone, with benefits sustained over five years.
The data reinforced the potential of Moderna’s mRNA platform beyond COVID vaccines and triggered a sharp reassessment of its oncology pipeline. Shares jumped more than 15% on the day of the announcement.
Earlier in the month, Moderna also reported better-than-expected preliminary 2025 revenue of around $1.9 billion, outlined significant cost reductions, and guided toward a return to growth in 2026 with roughly 10% expected sales growth. The company said operating expenses were cut by about $2 billion in 2025 and confirmed regulatory filings were underway for its first mRNA-based flu vaccine following successful Phase 3 trials.
Together, strong clinical data and improving financial trends helped shift sentiment around the stock.
Seagate Technology ($STX) +48.04%
Seagate surged nearly 50% in January as demand for data storage continued to accelerate.
The company reported revenue of $2.83 billion for the December quarter, up 22% year over year, along with adjusted earnings per share of $3.11 and record gross margins. Management said enterprise and cloud customers are effectively buying all available nearline storage capacity, with orders sold out through 2026.
Seagate also raised its outlook, forecasting next-quarter earnings well above Wall Street expectations and modestly higher revenue, signaling continued strength in demand. The company is ramping production of its high-capacity HAMR hard drives, benefiting from a tight supply environment and favorable pricing.
Shares reached new highs during the month, building on a strong 2025 performance. Investors increasingly view Seagate as a core beneficiary of large-scale data storage needs tied to AI model training and data center expansion.
Worst S&P 500 Performers of January 2026
Among the steepest decliners were AppLovin, Intuit, and Humana. Each faced company-specific or policy-driven setbacks that pressured shares during the opening month of the year.
AppLovin Corp. ($APP) −29.79%
Mobile app and advertising technology company AppLovin started 2026 under pressure after a short-seller report weighed heavily on investor sentiment.
In mid-January, research firm CapitalWatch published a report accusing AppLovin of facilitating a Southeast Asian money-laundering network. The allegations triggered an immediate selloff, pushing the stock down roughly 5% to 6% as markets digested the claims. AppLovin’s management denied the accusations, calling them false and misleading.
While shares recovered some losses later in the month, confidence was damaged. This marked at least the fourth short report targeting AppLovin over the past year. Although previous attacks did not lead to lasting impacts, they have reinforced perceptions that AppLovin’s fast growth and complex business model make it a frequent target.
The timing also hurt. AppLovin shares had more than doubled in 2025 and were trading at elevated valuation levels, leaving the stock vulnerable as investors became more cautious toward high-multiple growth names. By the end of January, AppLovin was down nearly 30% for the month and well below its 52-week highs, with investors looking ahead to upcoming earnings for clarity.
Intuit Inc. ($INTU) −24.68%
Intuit, the company behind TurboTax and QuickBooks, fell almost 25% in January despite no major negative company-specific news.
The decline was largely driven by a broader pullback in high-valuation software stocks. Investors grew increasingly concerned that advances in artificial intelligence could disrupt traditional software business models, prompting a reevaluation of premium multiples across the group.
Intuit had previously reported solid quarterly results and reiterated full-year guidance for double-digit revenue growth. However, the company’s outlook for roughly 12% to 13% growth in 2026 represented a slowdown from around 16% last year, reinforcing concerns about moderating momentum.
Shares sold off sharply during several late-January sessions as cloud and SaaS stocks broadly declined. Intuit reached 52-week lows during the month, illustrating how valuation-driven selling can weigh on even fundamentally stable businesses when market sentiment shifts.
Humana Inc. ($HUM) −23.79%
Health insurer Humana slid sharply in January after a government policy proposal raised concerns about future reimbursement levels.
Late in the month, the Centers for Medicare and Medicaid Services released a proposed Medicare Advantage rate update for 2027 showing an effective increase of just 0.09%. This compared with roughly a 5% increase for 2026 and well below the 4% to 6% increase many in the industry had expected.
Humana is heavily exposed to Medicare Advantage, with about 85% of revenue tied to these plans. The proposal signaled potential pressure on margins and earnings growth, and raised fears that 2027 could mark the company’s first revenue decline in decades.
Humana shares dropped more than 20% in a single session following the announcement and continued to slide through month-end. Other large insurers also declined, but Humana fell the most due to its concentration in Medicare Advantage. By the end of January, the stock was down roughly 24%, placing it among the worst performers in the S&P 500 for the month.
This article is for informational purposes only and is not investment advice or a solicitation to buy or sell securities. The content is based on publicly available information and reflects the author’s opinions as of the publication date, which may change without notice. All investments carry inherent risks, including the potential loss of principal, and past performance is not indicative of future results. Readers should conduct their own research or consult a financial advisor before making investment decisions. BBAE holds no position in the securities mentioned, nor are they compensated by the companies mentioned.
