US benchmark equity indexes closed mixed on Monday, as investors evaluated the US credit ratings downgrade by Moody's.

The Nasdaq was flat at 19,215.46, while the S&P 500 increased 0.1% to 5,963.60. The Dow Jones Industrial Average was up 0.3% to 42,791.94. Among sectors, healthcare posted the largest gain while energy saw the steepest decline.

US Treasury yields were lower, with the 10-year rate decreasing 2.1 basis points to 4.46% and the two-year rate falling 3.7 basis points to 3.98%.

June West Texas Intermediate crude oil increased 0.3% to $62.15 a barrel on Monday.

In economic news, Moody's lowered the world's largest economy's long-term issuer and senior unsecured ratings to Aa1 from Aaa on Friday, citing a sustained increase in debt and interest payment ratios. Moody's revised its outlook on the US to stable from negative.

"Large fiscal deficits will drive the government's debt and interest burden higher," Moody's said. "The US' fiscal performance is likely to deteriorate relative to its own past and compared to other highly-rated sovereigns."

Atlanta Fed President Raphael Bostic said he prefers only one rate cut in 2025 for now, CNBC reported. Bostic reportedly said that tariffs have been larger than the Fed anticipated at the start of the year.

In company news, UnitedHealth Group (UNH) shares surged 8.2%, the top gainer on the S&P 500 and the Dow.

Dollar General (DG) shares were up 4.9%. Goldman Sachs and Morgan Stanley raised the price target on the company's stock to $96 from $85 and to $85 from $80, respectively.

BGC (BGC) said it has agreed to repurchase nearly 16.5 million shares of its class A stock that is owned by its former Chair and Chief Executive, Howard Lutnick, who is now the US Secretary of Commerce. BGC shares jumped 8.9%.

First Solar (FSLR) was the worst performer on the S&P 500, down 7.6%. Goldman Sachs raised its price target on the company's stock to $255 from $204, while Barclays increased it to $222 from $204.

Gold increased 1.6% to $3,236.70 per troy ounce, while silver was up 0.5% to $32.52 per troy ounce.