In late afternoon trading in New York, the Dow Jones Industrial Average added 0.17 per cent. The Standard & Poor's 500 Index fell 0.13 per cent and the Nasdaq Composite Index dropped 1.1 per cent.
Bucking the trend, shares of Apple rose, last up 0.3 per cent at US$101.93 after earlier rising as high as US$103.05, after the company said it received a record four million first-day pre-orders of its new iPhone 6 and iPhone 6 Plus.
"Demand for the new iPhones exceeds the initial pre-order supply and while a significant amount will be delivered to customers beginning on Friday and throughout September, many iPhone pre-orders are scheduled to be delivered in October," Apple said in a statement.
Meanwhile, the Organization for Economic Cooperation and Development downgraded its growth forecasts for some of the world's major developed economies including the US, euro zone, Japan, and Germany.
US gross domestic product will expand 2.1 per cent in 2014, down from a May forecast for 2.6 per cent, euro-zone GDP will grow 0.8 per cent this year, down from 1.2 per cent in May, the OECD said in a report.
"Global growth should be somewhat more vigorous in the second half of 2014 and into 2015 given continued policy support, favourable financial conditions and growing confidence, alongside rising employment," according to the OECD. "Monetary conditions ought to remain supportive in all the major advanced economies, while most countries need to make further progress on fiscal consolidation to ensure that debt burdens remain sustainable."
The OECD said it was concerned about the optimism reflected in equity and bond markets.
"The bullishness of financial markets appears at odds with the intensification of several significant risks," according to the OECD. "A number of equity markets are reaching record highs, sovereign bond yields in several countries are near all-time lows and implied share price volatility in the United States and Europe is around pre-crisis levels. This highlights the possibility that risk is being mispriced and the attendant dangers of a sudden correction."
In Europe, the Stoxx 600 finished the session with a 0.1 per cent slide from the previous close. The UK's FTSE 100 Index slipped 0.04 per cent, while France's CAC 40 declined 0.3 per cent. Germany's DAX rose 0.1 per cent.
Shares of SABMiller soared 9.8 per cent while Heineken Holding rose 3 per cent. Heineken said it rejected a takeover offer from SABMiller and that it intends to remain independent.
"The Heineken family has informed SABMiller, Heineken and Heineken Holding NV of its intention to preserve the heritage and identity of Heineken as an independent company," the company said in a statement. "The Heineken family and Heineken NV's management are confident that the Company will continue to deliver growth and shareholder value."
The spotlight on industry consolidation helped other beer stocks. Shares of Molson Coors Brewing jumped 7.3 per cent, while those of Anheuser-Busch InBev added 2.8 per cent.