The Conference Board's index rose to 133.4 in August, despite expectations from a survey of Reuters' economists that it would fall to 126.7. The measure rose slightly last month to 127.4, up from 127.1 in June as consumers reported better feelings toward the economy in the near-term but less optimism about long-term growth.
The Treasury Department auctioned $37 billion in five-year notes at a high yield of 2.765 percent. The bid-to-cover ratio, an indicator of demand, was 2.49. Indirect bidders, which include major central banks, were awarded 66.2 percent. Direct bidders, which includes domestic money managers, bought 9 percent.
Overall, market participants around the world are digesting news surrounding the U.S. and Mexico, who secured a new trade deal on Monday.
According to President Donald Trump, this pact would be named "The United States-Mexico Trade Agreement," replacing the current NAFTA agreement and name; and is set to last for 16 years, with a review taking place every six years. Negotiations with Canada have yet to commence, but the U.S. leader added that if Canada chose to negotiate fairly, the U.S. would be open to that.
—CNBC's Kayla Tausche and Fred Imbert contributed to this report.