Alibaba is the next major China tech giant to post earnings after Tencent posted earnings in mid-August. Tencent's profit fell, which sent the stock lower and raised broader concerns about China's economy. This helped push the broader U.S. stock market lower.
On Friday, Powell's speech could spark volatility in the markets, largely because trading volume will be particularly light as the speech is delivered on one of the final Fridays of August.
Investors await commentary on the central bank's interest rate path for 2018 and whether the recent volatility in emerging markets may change that outlook.