A dramatic closing to the month saw Amazon and Apple deliver significant market-cap swings, influencing the Nasdaq's performance. Apple's stock experienced a steep 7.4% decline, marking its largest one-day market cap loss on record at $357.8 billion. This drop followed disappointing September quarter forecasts.

Conversely, Amazon's stock surged 15% after reporting accelerated cloud-computing sales, resulting in its largest market-cap gain ever. These opposing movements created a tug-of-war within the Nasdaq, which ultimately closed with a 1% gain.

The tech sector, heavily influenced by Apple, fell 0.5%, while the consumer-discretionary sector, boosted by Amazon, rose 6.1%. The S&P 500 gained 0.7%, and the Dow industrials advanced 0.5%. For the month of July, the Dow ended up 0.3%, the S&P 500 was down 0.1%, and the Nasdaq slipped 3.2%. All three indexes saw gains of 1% or more for the week.