01:46 PM EDT, 09/10/2024 (MT Newswires) -- US equity indexes were mixed in choppy midday trading on Tuesday, amid a decline in government bond yields and a sharp selloff in crude oil.

The Nasdaq Composite rose 0.4% to 16,944.5 and the S&P 500 index climbed less than 0.1% to 5,474.8. But, the Dow Jones Industrial Average fell 0.5% to 40,621.3. Real estate and consumer discretionary led the top gainers intraday, while energy and financials were the steepest decliners.

In economic news, the National Federation of Independent Business' monthly Small Business Optimism Index fell to 91.2 in August, more than reversing a gain to 93.7 in July. It was below the 91.3 print a year earlier.

"Historically high inflation remains the top issue for owners as sales expectations plummet and cost pressures increase," said NFIB Chief Economist Bill Dunkelberg. "Uncertainty among small business owners continues to rise as expectations for future business conditions worsen."

Treasury yields fell, with the 10-year yield down 4.7 basis points to 3.65% and the two-year rate 6.5 basis points lower at 3.6%.

Further, in economic news, Redbook US same-store sales increased by 6.5% from a year earlier in the week ended Sept. 7 after a 6.3% year-over-year increase in the previous week. Redbook said higher sales were due to Labor Day promotions, especially on Sunday and Monday, as the back-to-school season peaked.

West Texas Intermediate crude oil plunged 4.3% to $65.76 a barrel.

Oil prices slumped amid demand concerns as the August economic data from China, the world's largest oil importer, showed producer-price disinflation. Meanwhile, Tropical Storm Francine forced the closure of some Gulf of Mexico platforms, cutting supply.

China is struggling to incentivize spending, PVM Oil Associates said in a note, while adding that the "purchase of foreign crude oil dropped 7% on the year."

The first debate between former President Donald Trump and Vice President Kamala Harris will likely begin at 9:00 p.m. ET.

"Our base case remains for gridlock, with divided government or small majorities unable to pass large, catch-all bills," a research note from the Wells Fargo Investment Institute said. "Given this backdrop and other factors, we think the economy is much more likely to move markets than elections."

In company news, Oracle (ORCL) shares soared more than 12% intraday, the top performer on the S&P 500, after multiple price target hikes from analysts, following the company's fiscal Q1 results. The database management group reported, late Monday, higher fiscal Q1 non-GAAP earnings and revenue, which exceeded the average analyst estimates from Capital IQ.

Hewlett Packard Enterprise ( HPE ) shares slumped 7.5% intraday, the worst performer on the S&P 500 after the company unveiled a $1.35 billion offering of convertible preferred shares.

Gold rose 0.4% to $2,542.61 an ounce, while silver slipped 0.1% to $28.61.