The White House does not feel pressure to loosen restrictions on U.S. oil exports further and views debate over the issue as resolved for now, John Podesta, a top aide to President Barack Obama, told Reuters in an interview.

British elections in May could arguably have as much impact on euro zone stability as this month's snap poll in Greece, making for an anxious period of up to six months for European investors.

The euro slumped to a nine-year low on Monday as investors bet that the prospect of inflation across the region turning negative and mounting political uncertainty in Greece will force the European Central Bank to unleash quantitative easing.

U.S. crude and Brent futures dropped to fresh 5-1/2-year lows on Monday as worries about a surplus of global supplies amid weak demand continued to drag on oil markets.

China's growth engine looks to have ended last year on a flat note as its massive factory sector sputtered in December, though ebbing price pressures also offered scope for more policy stimulus from Beijing and across much of Asia.

U.S. drug approvals in 2014 hit their highest level in 18 years and recommendations in Europe also came at a rapid rate, driven by expensive new treatments for cancer and rare diseases.

China's factory activity sputtered in December, underlining the challenges facing the country's manufacturers as they fight rising costs and softening demand in a cooling economy.

Revelers ringing in of the new year this week need to watch out for the next day's hangover. And investors may experience a similar feeling early in 2015 after a two-year run that has propelled U.S. stocks up by nearly 50 percent.

The dollar was on track to end 2014 with a gain of 12 percent against a basket of major currencies, and anticipated U.S. interest rake hikes may strengthen its appeal in the new year.

Excelerate Energy's Texan liquefied natural gas terminal plan has become the first victim of an oil price slump threatening the economics of U.S. LNG export projects.