Amazon and Microsoft Add $400 Billion in Market Cap in One Day

Amazon and Microsoft are on track to add a combined $400 billion in market capitalization in a single trading session, according to Dow Jones Market Data. Amazon shares jumped 7.1% in midday trading Wednesday, while Microsoft gained 7% — putting Amazon on pace to add $187 billion and Microsoft on track to gain $250 billion in market value.

The surge followed the midterm elections, and analysts point to a combination of factors behind the move. John Belton, a portfolio manager at Gabelli Funds, told MarketWatch that constraints on data-center construction could actually work in the two companies' favor.

Why could a data-center slowdown help Amazon and Microsoft?

Texas Governor-elect Gina Hinojosa campaigned on an immediate moratorium on data-center construction until the state government can issue rules around the buildout. Incumbent Greg Abbott issued a temporary pause on data-center permits in September, although a report from watchdog group FracTracker with Public Citizen found that permitting continued after the order.

Investors in some corners of the tech sector are worried about new data-center restrictions now that Democrats have won control of Congress and key gubernatorial seats. But Microsoft and Amazon investors may be reasoning that a slower approach to data-center development isn't such a bad thing.

With demand for computing power expected to keep outstripping supply, "any incremental constraint on future data-center capacity" could let incumbent cloud-service providers like Amazon and Microsoft raise prices, Belton said. Higher prices could mean better margins — and better profitability — for the two companies.

What else is driving the rally?

There's also a case that Microsoft and Amazon could slow data-center spending in this new political environment. Investors may welcome that, given that AI investments have been eating into the cash these companies generate.

Ivan Feinseth, an analyst at Tigress Financial Partners, told MarketWatch the two stocks are benefiting from "a combination of post-election relief, declining policy uncertainty, renewed investor enthusiasm for AI and cloud computing and significant short covering."

Investors had positioned for a post-election selloff, Feinseth said, and they're now "unwinding" from defensive positions.

How did the rest of big tech trade?

The rally extended beyond the two cloud leaders. Alphabet, also a major cloud provider, saw its shares rise about 4% Wednesday afternoon. Meta Platforms' stock was in the green as well, up 1.2%.

The gains weren't universal across tech, though. Chip stocks including Micron slipped as election results struck at the core of data-center optimism elsewhere in the market.

What happens next?

Feinseth sees the election as a near-term catalyst for tech stocks like Amazon and Microsoft. But the "more sustainable drivers," he said — continued AI demand and infrastructure spending — will move these stocks over the long run. That framing suggests Wednesday's pop is the beginning of a repricing, not a one-day event, if AI demand keeps running ahead of data-center capacity.