HARD TRANSITION AHEAD

"The transition from failed country to global power is likely to be both bumpy and slow," said Roberto Lampl, Head of Latin American Investments at Alquity Investment Management. "Macri will have to undo twelve years of damage but looks set to prioritise the economy and growth."

"Today there is an optimism in Buenos Aires which hasn't been seen for over a decade, change has finally come to Argentina."

Scioli, a moderate Peronist, had the support of Fernandez loyalists but he failed to convince others he would restore investor confidence at a time when Argentina seeks to exploit vast shale oil and gas reserves.

Even so, his warnings that Macri's pro-market policies will put the interests of big business ahead of workers, erode salaries and destroy pensions have laid down possible battle lines between Macri and his opponents over the next four years.

"If Macri devalues then people could go out into the streets and protest," said Scioli voter Ana Marchessi, a 56-year-old lawyer.

Macri's margin of victory was less than 3 percentage points and his challenge will be to show an economic recovery is taking root by late 2016 or he could face a hammering in a mid-term Congressional elections the following year.