Experts predict more falls.
Google and YouTube parent company Alphabet posted weaker-than-expected revenues and earnings. Slower advertising spending meant Alphabet shares tumbled 7% in after-hours trading.
Microsoft also fell after its latest guidance, while Apple's shares were up just 0.2% at the close of trading.
Futures markets are predicting a 2% fall for the tech-focused Nasdaq when trading resumes on Friday morning.
Profits at Barclays hit £2 billion in the third quarter, resulting in a surplus of £5.7 billion for the year to date. The bank's quarterly profit is 6% higher than the figure for the previous year and up from £1.8bn a year earlier.
Online furniture retailer Made.com has suspended customer purchases after failing to find a buyer. In recent months, the company has warned it would need £70 million in funding to secure its future over the next 18 months.