The U.S. stock market faced heavy selling pressure on Thursday, 5 Nov 2026 GMT+7, amid expectations that the Democratic Party might secure a significant victory in the U.S. midterm elections. This raised investor concerns, especially regarding the risk of tighter regulations and restrictions on Data Center construction, potentially impacting future AI infrastructure investments.
Selling pressure spread across the market, particularly affecting technology stocks and companies in the AI supply chain. As a result, the market capitalization of firms in the S&P 500 index declined by approximately $3 trillion, or about 100 trillion baht, in a single day, erasing gains from the previous strong trading day, which had been the best performance in three months.
The S&P 500 index fell 4.36%, its largest drop since the Liberation Day tax crisis in April 2025, while the Dow Jones dropped 1,833 points or 3.44%. The Nasdaq Composite plunged 5.52%, pushing the index into a correction after declining 11.9% from its all-time high reached in October.
This sell-off was not limited to U.S. markets but also affected international stock markets. South Korea's Kospi index dropped 5.3%, Japan's stock market fell about 1.8%, and European and UK markets declined roughly 0.4%, reflecting pressure on risk assets amid concerns about the future of AI investment.
One striking figure illustrating the severity of the sell-off is the combined market capitalization loss of the 'Magnificent Seven'—Apple, Microsoft, Alphabet, Amazon, Nvidia, Meta, and Tesla—which fell by more than $1 trillion, or about 33 trillion baht, in a single day.
Nvidia, the world's leading AI chipmaker, was the most heavily impacted stock, dropping approximately 9.3%. This decline erased over $440 billion, or roughly 14.7 trillion baht, of its market value in one day.
This decline caused Nvidia's year-to-date returns in 2026 to turn negative 2.6%, after previously being among the top-performing stocks driven by AI investment trends in recent years.
Nvidia also exerted the greatest downward pressure on the S&P 500 index due to its very large market capitalization, meaning even small price changes significantly influence the overall index direction.
Other companies in the AI industry supply chain also faced heavy selling. Advanced Micro Devices (AMD) fell 17.3%, CoreWeave, a cloud-based AI computing service provider, dropped 9.8%, and GE Vernova, which supplies energy infrastructure for Data Centers, declined 7.5%.
The damage extended beyond chipmakers to businesses benefiting from AI expansion, including cloud service providers, data storage systems, and the energy sector.
Examining sector movements, all 11 S&P 500 industry groups closed lower, indicating broad-based selling beyond AI or large technology companies.
The Information Technology sector suffered the most, falling 7.30%, marking its steepest single-day drop since 16 March 2020 during the COVID-19 crisis, when tech shares plunged as much as 13.92%. Industrials declined 4.12%, their largest single-day drop since April 2025.
The Technology Select Sector SPDR Fund (XLK), which invests in large U.S. tech stocks, fell 8.04%, also marking its largest daily decline since March 2020.
Notably, the Philadelphia Semiconductor Index (SOX), representing major chip manufacturers, fell about 12%, recording the second-largest single-day drop in its history.
Semiconductor stocks were heavily affected, with SanDisk down about 22%, and Micron Technology, AMD, and Marvell Technology each dropping around 17%.
These declines reflect investor concerns that slower Data Center construction could reduce demand for AI chips, memory, storage systems, and related equipment below market expectations. Semiconductors, as direct beneficiaries of massive AI investments in recent years, became the first group investors reduced risk exposure to amid growing uncertainty in investment trends.
A key factor behind the sell-off was the midterm election results on 6 Nov 2026 GMT+7, which indicated the Democratic Party was likely to secure a significant victory and regain majority control in both houses of Congress. This prompted investors to reassess risks related to U.S. economic and technology policies.
The AI industry, which had benefited from accelerated Data Center investments nationwide, is now facing public opposition in many areas over concerns about energy use, water consumption, utility costs, and impacts on household electricity bills.
Reports show that in this election, 45 local proposals related to Data Centers were on the ballot, with 39 aimed at restricting AI infrastructure expansion approved. This indicates that Data Centers have shifted from a technological investment issue to a political and public cost-of-living concern.
UBS analysts estimate that risks from suspending or delaying construction projects could affect about 30% of the planned new Data Center capacity in the U.S. through 2028.. (No translation needed as the part is incomplete)Although this figure is only a risk assessment of capacity, it is sufficient to make investors question the growth prospects of companies in the AI supply chain.
This shift also highlights an interesting dynamic in the U.S. stock market: on Wednesday, investors reacted positively to the election results, viewing the change in congressional power balance as potentially reducing policy uncertainty under the Trump administration.
However, just one day later, the market began weighing the potential impacts on the AI industry more heavily, especially the possibility of stricter regulations and construction limits on Data Centers.
The election results do not automatically mean AI investments will be halted, nor are they the sole reason for the tech sell-off. The market also faces concerns over rising financial costs and high earnings expectations for technology companies.
In recent months, the market has increasingly questioned the value of AI investments, particularly companies rapidly expanding processing capacity ahead of demand, still needing to prove they can generate sufficient revenue and cash flow to justify their investments.
What remains to be watched is whether AI-driven investment, a key factor in the U.S. economy, can sustain its growth rate.
If many Data Center projects are delayed, the impact could ripple through orders for AI chips, storage equipment, network systems, and energy demand—all businesses that have benefited from the recent AI boom.
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