Gains by technology companies lifted the Nasdaq early Tuesday before congressional testimony from the head of the Federal Reserve and the US Treasury secretary.
Semiconductor shares rose following good earnings from Micron, and large tech companies such as Amazon and Netflix also gained around one percent, offsetting worries stirred by higher coronavirus counts in many states.
About 15 minutes into trading, the tech-rich Nasdaq Composite Index was up 0.6 percent at 9,937.54.
The Dow Jones Industrial Average slipped 0.1 percent to 25,575.62, while the broad-based S&P 500 added 0.3 percent at 3,062.66.
In prepared remarks ahead of the midday hearing, Fed Chair Jerome Powell said the US economy had begun rebounding faster than expected, but that the "path forward for the economy is extraordinarily uncertain" and depends on containing the coronavirus.
The hearing comes as numerous states have suspended or rolled back steps to reopen the economy due to rising COVID-19 cases.
Wells Fargo was down 0.2 percent and underperforming other large banks after it announced it would trim its dividend by an undisclosed amount from 51 cents per share.
The large bank also said it expects "substantially higher" provisions for credit losses in the second quarter compared with the first quarter due to the economic hit from the coronavirus.
Boeing plunged 5.4 percent after Norwegian Air Shuttle announced it cancelled an order for 92 Boeing 737 Max aircraft and five Dreamliners.
The decline gave back some of the 14.4 percent the company gained on Monday as US air safety regulators undertook a long-delayed test flight of the 737 MAX, which has been grounded since March 2019 following two crashes.