(Adds S&P downgrade)
By Gabriel Stargardter
BUENOS AIRES, Aug 16 (Reuters) - Ratings agencies Fitch and Standard & Poor's downgraded Argentina's sovereign debt rating on Friday, flagging higher chances of a default in the wake of a shock primary election result that plunged the country into its latest economic crisis.
Argentine markets were in free-fall for most of the week after Sunday's vote when center-left presidential candidate Alberto Fernandez trounced center-right President Mauricio Macri. The scale of Fernandez's victory suggested he could win the October ballot in the first round, potentially putting an end to free-market economic reforms and an IMF-backed austerity plan.
The downgrades cap a tough week in which the peso lost nearly 20% of its value, forcing the central bank to eat into its reserves with dollar auctions. Fitch downgraded Argentina's sovereign debt rating from 'B' to 'CCC,' while S&P lowered its rating to 'B-' from 'B.'
"The downgrade of Argentina's ratings reflects elevated policy uncertainty following the primary elections, a severe tightening of financing conditions, and an expected deterioration in the macroeconomic environment that increase the likelihood of a sovereign default or restructuring of some kind," Fitch said.
Fitch said it expected Argentina's economy to contract 2.5% in 2019, down from a previous forecast of 1.7%. Fitch added that it saw government debt rising to around 95% of gross domestic product in 2019.
S&P saw 2019 growth falling 2.3%, compared with a prior forecast of a 1.6% decline.
Alejo Czerwonko, emerging markets strategist at UBS Global Wealth Management's Chief Investment Office, said the downgrade was not going to substantially change many people's minds about the solidity of Argentine debt.
"Argentina was already rated deep into junk territory and this is pushing the rating a bit deeper, but it reveals little new information to investors," he said.
While Fitch said it expects growth to be flat in 2020, S&P saw 2020 growth at 0.5%, compared with a prior forecast of 2.2%, highlighting uncertainty over the policies of Fernandez.
Fitch said the chances of Fernandez winning the election had grown, raising doubts about the future of Macri's IMF-backed austerity plan. The fact that Fernandez's running mate is leftist former President Cristina Fernandez de Kirchner, a longtime skeptic of the IMF program, only heightened those doubts, Fitch said.
"We could lower the ratings over the next 12-18 months if economic and financial stresses continue to mount," S&P said, adding it saw "a greater than one-in-three chance of a downgrade over the coming year."
(Reporting by Gabriel Stargardter; Additional reporting by Rodrigo Campos in New York Editing by Marguerita Choy and Tom Brown)