US Federal Debt Ceiling Vote and Possible Federal Reserve Rate Hikes Prompt Market Uncertainty

Wall Street closed lower Wednesday over concerns about the federal debt ceiling vote in Congress and a possible interest rate increase by the Federal Reserve.
Traders estimate a 70% chance of a 0.25% rate hike at the Federal Reserve's September meeting.
Positive developments in US debt ceiling negotiations and the Chinese economy could lead to slight gains at the opening bell.
The US dollar and oil prices declined due to lower expectations of rate hikes and increased crude oil stockpiles.
Salesforce stock fell over 5% following weak sales growth.