Investors tempted to jump in on buying stocks in Brazil should be very cautious and not tempted by thoughts of an easy way to make a fast buck.

President Jair Bolsonaro and his administration have drawn up an ambitious economic reform agenda, which foreign investors have welcomed.

For example, an overhaul of Brazil’s pension system could save up to 1.3 trillion reais ($345 billion) over the next decade, Economy Minister Paulo Guedes recently told Reuters, aiming as much as two-thirds higher than the previous government’s failed effort.

“Foreign investors had a series of problems with emerging markets last year. But I was in New York in December ... and investors are quite optimistic: they like the economic agenda we’ve presented,” Mansueto Almeida, Secretary of Brazil'sTreasury, told Reuters.

However, the danger is that the market is pricing in reform more or less on the government’s terms—far from a done deal, Barron's warns. Through Wednesday, the iShares MSCI Brazil exchange-traded fund (ticker: EWZ) had soared 17% this year, versus 9% for all global emerging markets. And the real is up 6% against the dollar.

However, anything less than 1 trillion reals in pension cuts could dent investors’ confidence in Brazil, says Richard Thies, an emerging-markets portfolio manager at Driehaus Capital Management.

“Expectations are so high that any slip up could be negative,” Thies told Barron's.

To be sure, other experts agree. “Bolsonaro was elected to combat corruption and crime, not to enact social security reform,” says Paulo Sotero, director of the Brazil Institute at the Wilson Center in Washington. “I would be very careful before betting on this.”

Verena Wachnitz, portfolio manager for Latin American equities at T. Rowe Price, told Barron's that success on the pension front could unleash reform of Brazil’s tortuous tax system and a privatization wave that could re-rate share multiples upward. But for now, watch the congressional maneuvering closely.

However, assuming that doesn’t prove to be a disaster and that Bolsonaro doesn’t fail altogether on pensions, the president could command support for his programs.

The No. 9 global economy is rebounding from a profound recession as the rest of the world slows, and is gripped by optimism, while electorates elsewhere turn grumpy and self-doubting. “It’s pretty shocking that this is the same country I visited a year ago,” Driehaus’ Thies says. “Things here feel very early-cycle.”

Other experts also have warned that investor be carerful.

While developing-nation stocks just completed their best month since March 2016, and currencies scored the biggest monthly gain in a year, only those that meet three key criteria -- solid growth, benign inflation and no significant political risks -- are worth chasing, he said. And that leaves him with countries such as Indonesia and Brazil.

“It’s going to be a year where you’ve got to be selective with your emerging-market bets,” Tokyo-based Matsumoto told Bloomberg. “A dovish Fed has given some leg to the recent emerging-market rally, but I don’t expect this to lead to the kind of Goldilocks environment we saw back in 2017.”

“Sure, the bears might have disappeared more, but I don’t think investors are going overweight aggressively,” he said.

Material from Bloomberg and Reuters has been used in this report.