The Federal Reserve could set a more measured pace for interest rate hikes, according to hints from Powell.
The Facebook parent's earnings call caused stock futures to fall.
The Fed raised interest rates. The chair of the US central bank said its decisions on policy will be driven by data in the future, a shift that suggests the Fed could pause or slow its tightening if the economy gets worse.
There was hope that aggressive Fed rate hikes would not lead to a downturn in the US.
The world index put on a small amount of points. The pan-continental Stoxx 600 was up. The Paris's CAC 40 tipped 0.05% lower as the London's FTSE 100 slid.
The Hang Seng in Hong Kong lost 0.23%, while the Shanghai Component closed 0.21% higher. The Japanese stock market closed lower.
The S&P 500 finished 2.62% in the green after Powell's comments and US stock futures were trading lower in European trading.
The S&P 500 futures were down. The futures of the blue chip index held a little better but slipped.
Equity futures are going to take a hit after the big moves. When US markets reopen later, there may be a bit of profit taking.
Meta's disappointing second-quarter earnings report was one of the factors that weighed on sentiment.
The company's earnings came in at $2.46 a share, which was better than the $2.59 expected. The stock was down before the market opened.
"We seem to have entered an economic downturn that will have a broad impact on the digital advertising business."
He said that the situation seemed worse than it did a quarter ago.
After a warning of a faltering digital ad market last week, investors are keeping a close eye on this week's stream of earnings reports. There are quarterly updates from Apple and Amazon.
The first reading on US second-quarter GDP could feed into the Fed's approach. The PCE index will be updated on Friday.
Oanda senior market analyst Jeffrey Halley said that US GDP could well print a second negative quarter. A negative print will likely cause the stock market to rally and the US Dollar to fall. If tomorrow's PCE Index data shows signs of waning, it could lead to a repeat.
Other major assets are doing well.