In the latest indication of the trade dispute hurting businesses, German chemicals giant BASF warned of a 30pc fall in adjusted annual profit, while RBC Capital Markets downgraded 3M Co to "sector perform", citing macro pressures from China, auto and electronics sectors.
The industrial conglomerate's shares fell 1.4pc and pulled down the S&P industrial sector 0.45pc, the most among nine of the 11 major S&P sectors trading lower.
China-exposed stocks slipped. Boeing Co, the single largest US exporter to China, dipped 0.3pc ahead of release of its orders and deliveries for the second quarter, while Caterpillar Inc declined 0.5pc.
The Philadelphia chip index edged 0.21pc lower, as chipmakers, which get a large chunk of their revenue from China, fell.
Stocks have retreated from their record closing highs since a robust June jobs report on Friday tempered expectations of an aggressive 50 basis point rate cut by the Fed.
"There is certainly nervousness over ... the fact that no (trade) agreement has been reached nor seems that close and that the recent jobs report calls into question how quickly the Fed is likely to lower rates," said Rick Meckler, partner, Cherry Lane Investments in New Vernon, New Jersey.
"Without the two items being favorably resolved, it's hard for the market to push to even higher levels when it has gained already so much this year."
The United States and China are set to relaunch trade talks this week after a two-month hiatus, but a year after their trade war began there is little sign their differences have narrowed.
Focus this week will be on Fed chief Jerome Powell's remarks at his two-day testimony before the Congress, starting Wednesday. Also due on Wednesday is the central bank's June policy meeting minutes.
At 9:37 a.m. ET, the Dow Jones Industrial Average was down 74.98 points, or 0.28pc, at 26,731.16. The S&P 500 was down 6.77 points, or 0.23pc, at 2,969.18 and the Nasdaq Composite was down 10.23 points, or 0.13pc, at 8,088.16.
Banking stocks were down 0.29pc ahead of a conference by the Fed to discuss the effectiveness of its stress tests for large lenders.
Network gear maker Cisco Systems Inc slipped 0.4pc on a deal to buy optical component maker Acacia Communications Inc for $2.84 billion in cash. Acacia's shares soared 34.9pc.
Second-quarter earnings season is expected to start in earnest next week, where profits at S&P 500 companies are set to dip 0.2pc from a year earlier, according to Refinitiv IBES data.
Declining issues outnumbered advancers for a 2.47-to-1 ratio on the NYSE and for a 1.70-to-1 ratio on the Nasdaq.
The S&P index recorded seven new 52-week highs and no new low, while the Nasdaq recorded 10 new highs and 14 new lows.