Microsoft added more market cap in a single session than 96% of S&P 500 constituents

Shares of Microsoft Corp. were a part of history on Thursday, July 30, after adding nearly half a trillion dollars to its market cap, the most that any stock has added in a single session, on record.

Microsoft shares rallied 15% overnight in response to its quarterly results, marking their best single-day gain since October 2008.

The rally meant that Microsoft added nearly $450 billion to its market capitalization, surpassing Nvidia's $440 billion addition back in April 2025, which is when US President Donald Trump had announced a first pause on his reciprocal tariffs, which had roiled global markets.

Microsoft's $450 billion jump in market cap in a single session is higher than the market capitalization of nearly 96% of the S&P 500 constituents. It is also bigger than the combined market cap of 41 smallest companies of the index, which includes names like Domino's Pizza, Clorox, and Hasbro.

Not only companies, the market cap addition seen in Microsoft was also higher than the market cap of markets such as South Africa, Finland, Vietnam and Turkey.

Microsoft reported strong results during the quarter, which not only surpassed expectations, but also saw strong growth. Its Azure cloud unit grew by 43% during the fourth quarter of their fiscal year, which is the fastest pace of growth that the business has seen since early-2022.

The street also liked the fact that the company left its capex plans for the year unchanged at close to $175 billion, stating that they would only look at increasing that figure if they see a surge in work orders.

Shares of Microsoft ended 15.5% higher at $451.1. The stock is still well below its 52-week high of $555.45.