Wall Street slid paced by Boeing as investors worried about expenses for its 787 Dreamliner passenger jet, while oil fell after a report showed US inventories rose more than expected last week.
West Texas Intermediate crude for December delivery fell 1.5 percent. In afternoon trading in New York, the Dow Jones Industrial Average fell 0.57 percent, the Standard & Poor's 500 Index shed 0.35 percent, while the Nasdaq Composite Index declined 0.38 percent.
Part of the negative sentiment was linked to an attack by at least one armed man in Ottawa, Canada's capital. A soldier standing guard at the nation's war memorial was killed and the gunman, who ran into the main parliamentary building, was shot dead.
Slides in shares of Boeing and those of American Express, last down 3.8 percent and 1.6 percent respectively, propelled the Dow lower.
Shares of Boeing dropped amid mounting concern about costs for its 787 Dreamliner, overshadowing the company's upgrade in its earnings outlook as well as its better-than-anticipated third-quarter profit.
"The EPS beat was defense driven and not all of the news was encouraging," Joseph Nadol, a JPMorgan Chase analyst in New York, told clients in a note, according to Bloomberg News. "There was a drop-off in the core commercial margin and 787 cash losses did not slow as fast as we had forecast."
But it was not all bad news. Indeed, shares of Yahoo and Broadcom rose, up 4.9 percent and 6.2 percent respectively, after posting earnings that surpassed expectations.
"The season has been mixed, and the global economy is a concern for big multinational companies, but the fact that the market can shake off some bad reports is indicative of what good footing it is on right now," Bruce Bittles, chief investment strategist at Robert W Baird & Co in Nashville, told Reuters.
On the economic data front, a report showing the consumer price index rose 0.1 percent in September bolstered expectations the US Federal Reserve might hold off on raising interest rates longer than expected. Policy makers begin their next two-day meeting on October 28.
"The ongoing inflation weakness will give the Fed leeway to take a restrained approach to tightening monetary conditions," Robert Hughes, senior research fellow at the American Institute for Economic Research in Great Barrington, Massachusetts, told Reuters.
In Europe, the Stoxx 600 finished the day with a 0.7 percent advance from the previous close. The UK's FTSE 100 Index gained 0.4 percent, while both Germany's DAX and France's CAC 40 added 0.6 percent.
The European Central Bank reportedly bought Spanish covered bonds in a third day of asset purchases, lifting investors' mood about the outlook.
"The ECB buying bonds is just speculation, but investors are thinking there's no smoke without fire, so the sentiment is better," said Christian Stocker, a strategist at UniCredit Bank in Munich, told Bloomberg News. "The third quarter was bad for the economy in Europe."