In afternoon trading in New York, the Dow Jones Industrial Average edged 0.04 per cent lower, the Standard & Poor's 500 Index fell 0.20 per cent, while the Nasdaq Composite Index dropped 0.87 per cent.
Earlier in the session both the Dow and the S&P 500 set intraday record highs.
Gains in shares of Intel and American Express, up 1.8 per cent and 0.6 per cent respectively, offset declines in shares of Microsoft and Merck, down 0.9 per cent and 0.7 per cent respectively.
In Europe, the Stoxx 600 Index ended the day 0.1 per cent higher than the previous close, as did Germany's DAX. France's CAC 40 rose 0.4 per cent. The UK's FTSE 100 fell 0.2 per cent.
The European Central Bank kept its benchmark interest rate unchanged at a record low 0.25 per cent, as had been widely expected.
"We are resolute in our determination to maintain a high degree of monetary accommodation and to act swiftly if required," ECB President Mario Draghi said after the meeting in a statement. "Hence, we do not exclude further monetary policy easing and we firmly reiterate that we continue to expect the key ECB interest rates to remain at present or lower levels for an extended period of time."
"The Governing Council is unanimous in its commitment to using also unconventional instruments within its mandate in order to cope effectively with risks of a too prolonged period of low inflation," Draghi said. "The risks surrounding the economic outlook for the euro area continue to be on the downside."
Some analysts said Draghi's comment reflected a new urgency with regards to bolstering inflation to a higher level.
"Draghi tends to speak vaguely and just reiterate earlier speeches but he was more specific and aggressive this time round," Steven Santos, a broker at X-Trade Brokers, told Bloomberg News. "It looks like the ECB is increasingly pondering cutting the main interest rate and that the central bank might even come up with new measures soon. Markets clearly want more intervention from Draghi."