Stock futures rise; Citigroup and retail sales top expectations

U.S. stock-index futures rose on Monday after Citigroup reported quarterly earnings that topped analysts' expectations and March retail sales rose 1.1 percent, also surpassing estimates.

Citigroup gained after posting first-quarter earnings excluding items of $1.30 a share on $20.1 billion in revenue, compared to estimates of $1.14 a share on $19.36 billion in revenue.

"The weaker euro is helping to lift European markets off their lows, and Citi, which reported a better number is up. I think that's the combination for the lift in the markets," said Peter Boockvar, chief market strategist at the Lindsey Group.

Stock futures furthered their gains after data had retail sales rising 1.1 percent in March, up from the prior reading of 0.3 percent.

"The retail sales are a great barometer for the weather-related slowdown, and expectations across the board were beat," said Art Hogan, chief market strategist at Wunderlich Securities.

European shares had started lower, with technology stocks like Ericsson, STMicro and Alcatel-Lucent sharply lower.

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A weak earnings report on Friday from JPMorgan Chase prompted global markets to extend losses.

"Even if some investors weren't nervous about the beginning of earnings season before last week, they probably are now," Michael Hewson, a chief market analyst at CMC Markets, said in a morning research note.

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Ukraine said it plans to launch a "full-scale anti-terrorist operation" against pro-Russia rebels, according to Reuters. This came after the separatists took control of the Ukrainian city of Slaviansk over the weekend.