S&P 500: The Winners and Losers of August 2025
The S&P 500’s journey through early 2025 has been marked by dramatic volatility and a notable recovery. After starting the year with a 2.7% gain in January, the benchmark index faced headwinds in February and March. Since then, however, it has been growing steadily, recording four consecutive months of gains. In August, the index rose another 1.9%.
The broad-based rally was clear once again, with 335 of the 500 constituents posting positive returns in August.
In this article, we break down the top-performing and worst-performing S&P 500 stocks in August 2025 and explore the key news and developments that shaped their movements.
Top S&P 500 Performers in August
Among the top performers were Albemarle ($ALB), UnitedHealth Group ($UNH), and Intel ($INTC). Here’s a closer look at what drove each stock’s strong August rally.
Albemarle Corp ($ALB) +25.16%
Lithium Supply Shock: Albemarle, a major lithium producer, surged more than 25% in August as multiple factors aligned in its favor. Mid-month, China’s CATL—the world’s largest EV battery maker—idled a large lithium mine, tightening supply and lifting expectations for higher lithium prices, which directly benefits Albemarle.
Additional Tailwinds: Beyond the supply-driven boost, the company’s subsidiary Ketjen announced notable advancements in refinery catalyst technology, underscoring Albemarle’s innovation pipeline and operational efficiency. Meanwhile, organizational restructuring and leadership changes further bolstered investor confidence in its ability to adapt to shifting market conditions.
UnitedHealth Group ($UNH) +24.2%
Buffett’s Big Bet: UnitedHealth shares surged in mid-August after Warren Buffett’s Berkshire Hathaway disclosed the purchase of about 5 million shares—roughly a $1.6 billion stake. The stock jumped nearly 14% in a single day, as investors took the move as a strong vote of confidence in UnitedHealth’s long-term value. UnitedHealth Group ($UNH) emerged as the standout buy of the summer, with Buffett, Michael Burry, and David Tepper all stepping in after its steep decline.
Reinstated Outlook: Earlier in the summer, UnitedHealth unsettled markets by withdrawing its 2025 forecast due to rising medical costs. In late July, the company reinstated its full-year outlook. While the updated forecast came in lower than initial expectations, it removed uncertainty and restored some visibility into earnings.
The combination of renewed guidance and high-profile bets from heavyweight investors fueled a powerful rebound in UNH, which had been down nearly 40% year-to-date before August.
INTC Intel Corp +22.98%
U.S. Government Investment: After a long stretch of underperformance, Intel shares staged a sharp recovery in August. The turnaround was sparked by unprecedented government support: the U.S. government agreed to invest about $9 billion for roughly a 10% equity stake in the company. The move, effectively treating Intel as strategically “too big to fail,” sent shares up about 5.5% on the announcement alone. The cash infusion reassured investors that Intel has the backing needed to finance its turnaround.
Other Funding & Turnaround Plans: The government stake wasn’t the only boost. Earlier in August, SoftBank invested $2 billion in exchange for an equity stake, adding another layer of financial support. Meanwhile, new CEO Lip-Bu Tan has been aggressively restructuring—cutting thousands of jobs and prioritizing the revival of Intel’s foundry business. The combination of fresh capital, strategic restructuring, and optimism about winning new chip customers fueled a powerful rebound, lifting Intel more than 20% for the month after a long decline from its highs.
Worst S&P 500 Performers in August
Among the worst performers were Super Micro Computer ($SMCI), Gartner Inc. ($IT), and Eli Fortinet ($FTNT). These stocks struggled due to company-specific challenges and sector pressures.
Super Micro Computer ($SMCI) –26.62%
Disappointing Earnings and Guidance: Server-maker Super Micro, one of the big AI hardware plays, saw its shares tumble 26.6% in August after a weak fiscal Q4 report. Revenue came in below expectations, and earnings missed by a few cents. More damaging, management slashed its fiscal 2026 revenue outlook from $40 billion down to “at least $33 billion” and warned that Q1 earnings would likely fall short of analyst estimates. The guidance cut shocked investors, triggering a one-day 21% plunge on August 6.
Financial Control Worries: Adding to the pressure, Super Micro’s annual report disclosed “weaknesses” in financial controls and flagged a history of delayed filings. The company’s auditor had even resigned last year over governance concerns. While management insists these issues are being addressed, the disclosure raised fresh doubts about accounting reliability.
The combination of lowered growth expectations and renewed governance worries led many investors to exit the stock in August—though SMCI remains up significantly year-to-date, thanks to the broader AI boom.
Gartner Inc. ($IT) –25.8%
Guidance Cut Despite Solid Quarter: Shares of Gartner, a provider of IT research and consulting, sank nearly 26% in August after management issued a cautious outlook. Ironically, Q2 results were slightly ahead of expectations, with both revenue and adjusted profit topping Wall Street estimates. The problem came with guidance: Gartner cut its full-year sales forecast, and the revised revenue outlook fell below consensus.
Weakness in Research Segment: Management pointed to soft demand in its core “Insights” research unit, as business clients pulled back on IT spending amid economic uncertainty. The downbeat outlook shocked investors, driving the stock down almost 28% on the day of the announcement.
Concerns that even Gartner’s traditionally sticky, subscription-driven research business could face headwinds triggered a sharp sell-off, making IT one of the S&P 500’s worst performers in August.
Fortinet ($FTNT) -21.15%
Weak Guidance Overshadows Strong Results: Fortinet shares suffered one of their steepest drops on record after the company’s early August earnings report. On the surface, Q2 looked solid—revenue rose 14% year-over-year to $1.63 billion, and billings climbed 15%. But the market focused on guidance: Fortinet projected Q3 revenue slightly below expectations and cut its second-half 2025 service revenue outlook by $50 million. The weaker forecast, particularly in high-margin subscription services, raised concerns of a slowdown.
Firewall Slowdown Sparks Sell-Off: Management also pointed to softness in its core firewall hardware business, suggesting customers were stretching out upgrade cycles. These signals of slowing growth in both services and hardware triggered a sharp sell-off, with the stock plunging about 25% on August 7 and erasing a year’s worth of gains.
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.
