Mr Mattarella had rejected Mr Conte's original choice for finance minister.
Over the weekend, the Five Star Movement and the Northern League described Mattarella's opposition to Savona as unjustified and partisan, and alluded to his being part of a conspiracy to stop their government.
Paolo Savona, the eurosceptic economist who the populist coalition originally wanted for economy minister but was rejected by the italian president, is still part of the cabinet as European Affairs minister. The populists cried foul and abandoned their joint bid for power. The populist parties, which got the most votes in the inconclusive March election, have promised to vote against it in a confidence vote.
President Sergio Mattarella torpedoed an initial attempt by the League and 5-Star to form a coalition.More news: ABC execs considering 'Roseanne' spinoff without Barr
Malaysia's Bursa slipped up to 2.3 per cent to touch a more than five-month low, while the Indonesian index fell as much as 0.9 per cent ahead of a central bank policy meeting later in the day, where it is expected to raise its benchmark interest rate. The eurozone debt crisis of 2011 has long since passed, but concerns about Italy's ever-growing debt continue to mount as it's becoming increasingly clear the country's huge deficits will present a dilemma to global markets.
"It's taken the shine off markets which had been going very well recently, but at the moment I would say the sell-off looks to be of a smaller order than we've seen in previous incarnations of the euro zone crisis", Laith Khalaf, senior analyst at Hargreaves Lansdown, said.
"Still, it is well possible that the near-term financial market reaction is positive, as (the) breakthrough reduced the uncertainty and at least provides Italy with a much-needed government", he said.
"The next elections will be a plebiscite, the people and real life against the old castes and the Lords of the Spread", Salvini said, referring to financial speculators, in a statement issued by his League. While the president's approval is often perceived as pro-forma in Italy, there have been a few cases when the head of state refused to sign off on an appointment.
"None of those who in their lives have been critical of the European Union or of euro, can be a good fit for Minister of Economy", Di Maio said in an emotional live stream video on Sunday night.More news: Peru’s Guerrero Cleared To Play In World Cup After Cocaine Ban
Cottarelli, 64, was director of the IMF's fiscal affairs department from 2008 to 2013 and became known as "Mr Scissors" for making cuts to public spending in Italy.
The new government will be sworn in at 1400 GMT on Friday, a government official announced.
Di Maio kept his comments to a brief Facebook post thanking supporters and declaring "the government of change is reality".
Of course, the risks of an "Italexit" or of government default were only addressed in terms of probabilities, the expert explained, "but investors demanding a higher ten-year bond yield means they deem such risks stronger today than just one month ago".
Most opinion polls show Salvini's League would see huge gains in any early elections while the 5-Star would remain steady or see some gains.More news: Reasons the Cavs Could Win the NBA Finals