US equity indexes traded mixed after gains in Alphabet's (GOOG, GOOGL) shares helped lift the Nasdaq Composite while domestic fiscal jitters weighed over government bond yields.

The Nasdaq Composite rose 0.4% to 19,219.2 after midday on Wednesday. The S&P 500 fell 0.1% to 5,933.2, and the Dow Jones Industrial Average declined 0.7% to 42,377.6.

The communications services sector, home to Alphabet, was the top gainer and among the only two peer groups trading higher intraday. Utilities, energy, and financials led the decliners. Alphabet is an index constituent for both the S&P 500 and the Nasdaq.

Google is rolling out an "AI Mode," which answers queries in a chatbot-style conversation, Alphabet Chief Executive Sundar Pichai said at a developers conference Tuesday. The option is being added as a tab within search and initially for US users. Shares jumped 5.1% intraday, the top gainer on the S&P 500 and the Nasdaq.

The yields on 30-year and 10-year US Treasury bonds rebounded above key thresholds that roiled markets in April after President Donald Trump's tariff announcements. The 30-year yield traded at 5.02% and the 10-year yield was at 4.54% intraday.

BofA Securities analysts said they "do not think that the [US sovereign credit rating] downgrade [by Moody's Investors Service on Friday] matters by itself, but it has served as a wakeup call for those investors who had been ignoring the ongoing fiscal discussion."

House Republicans are girding for a vote on a messy budget reconciliation bill as soon as Wednesday night or Thursday, according to a note from Scotiabank.

"They still can't agree on the combination of tax cuts, spending cuts, and SALT deductions but are seeking to do so before heading off for the Memorial Day weekend," Derek Holt, head of capital market economics, said in the note. "If it passes in the House, then it's unlikely to pass in the Senate absent big modifications."

The ICE US Dollar Index, which measures the greenback's performance against the world's major currencies, fell 0.6% to 99.47.

Further, in company news, Target's (TGT) fiscal Q1 results fell more than estimated while the retailer slashed its full-year outlook, citing the impact of tariffs and uncertain consumer spending. Shares dropped 4.1% intraday.