S&P 500 falls 4.4%, its worst day since April 2025

Wall Street had its worst session since April 2025 on Thursday 5 November. The S&P 500 fell 334.89 points, or 4.36%, to 7,353.73. The Dow Jones lost 1,833.06 points (3.44%) to 51,523.06, and the Nasdaq Composite dropped 5.52% to 24,315, its biggest one-day fall in 19 months. The Russell 2000 fell 4.45%. The drop erased nearly $2.8 trillion of market value from the S&P 500, according to NBC News.

What happened

The trigger was not an inflation print or a bank failure. It was political. The Democratic sweep in the 3 November midterms opened the door to tougher scrutiny of the data centres behind the artificial-intelligence business. Senator Bernie Sanders called for a national moratorium on new facilities. Investors began to price in a slower buildout of AI infrastructure, and the sector that had led this year's rally became the first to fall.

The punishment was especially severe in semiconductors. The Philadelphia Semiconductor Index sank 12.25%, its second-biggest daily fall on record. Nvidia lost 9.3% and turned negative for the year; Micron and AMD fell around 17%; Broadcom dropped 10%. All 11 S&P 500 sectors closed lower, with technology down 7.30%, its worst session since March 2020. The Magnificent Seven lost more than $1 trillion of market value in aggregate.

The move did not stay inside tech. Caterpillar fell 6%, JPMorgan 4% and Boeing 2%, a sign that the fear spread across the market. The VIX volatility index jumped about 70% to 28.18. The 10-year Treasury yield fell to 4.84% and oil gained 3-4%.

Context matters. The S&P 500 is still up 7.4% year to date and more than 27% since the 2024 election. Thursday's drop took the index back to late-September levels but did not erase the year's rally. The Nasdaq, by contrast, gave back in one session more than it had gained on Wednesday, when the market celebrated the election result with its best day in months.

Similar falls in history

A 4% daily drop is unusual. Since 1946 there have been 63 sessions of that size, 0.31% of the total, and they tend to cluster: 40 of the 63 occurred within ten sessions of another, according to Finexus Research. The useful comparison is not only the percentage but what came next. These are some falls of similar magnitude and their subsequent recovery:

What history says about recovery

The first lesson is that there is no single template. After the ten worst daily falls in the S&P 500 since 1981, the index rose over the following year in nine out of ten cases and gained over three and five years in every case, according to Hartford Funds. The exception was 29 September 2008, the day the House rejected the first bank bailout: a year later the S&P 500 was still 4.1% lower. A 5.4% bounce the next day did not stop the financial crisis from continuing.

The second is that fast rebounds are common but not universal. In 2020, the 16 March fall was followed by a recovery of the previous level in 19 days and of the record high in five months; a year later the index was up 66%. In 2025, the 4 April tariff fall regained the February high in June, less than three months later. In 2022, by contrast, the 13 September fall opened the final phase of a bear market: the bottom came a month later and the previous high was not recovered until January 2024.

Averages can mislead. After sessions with falls of 4% or more since 1946, the S&P 500 has gained an average of 21.85% over the following twelve months and finished higher 84% of the time. Those figures are better than an average year, but they are inflated by the rebounds of 1987, 2020 and 2025. The distribution has two tails: days that mark a bottom and days that are only the first stop in a larger decline. In 2008, eight of the ten 4% falls with the worst one-year returns occurred early in the Lehman crisis.

What to watch now

The first technical level is the 200-day moving average, around 7,322. The S&P 500 closed just 0.4% above it. A close below would be the first since April and would confirm a change in the medium-term trend. The second is semiconductors: if headlines about data-centre moratoriums or regulation continue, the punishment could be repeated in the names that have risen most this year.

The financial transmission channel also matters. The VIX at 28.18 remains far from the panic levels of 2020, but it has risen sharply. The 10-year yield at 4.84% and the oil price shape the financing cost of AI projects. And the Federal Reserve has less room to ease policy if inflation does not cool: traders have pushed the expected timing of the next rate hike to March.

Politics will be decisive. The market did not react to the midterms with the usual playbook — more spending, lower taxes — but with a new question: how far can a Democratic majority slow the physical buildout of AI? The answer depends on rules that do not exist yet. Until they do, volatility has a reason and a specific sector to latch onto.