Brazilian President Luiz Inácio Lula da Silva's come-from-behind victory on Oct. 25 carries economic consequences well beyond Brazil.

Nov. 2 (UPI) -- Brazilian President Luiz Inácio Lula da Silva's come-from-behind victory on Oct. 25 carries economic consequences well beyond Brazil.

Lula defeated Sen. Flávio Bolsonaro 51.8% to 48.2% after trailing him in the first round. For Argentina's Javier Milei, Paraguay's Santiago Peña and Uruguay's Yamandú Orsi, the question is how to protect their economies when Mercosur's dominant member faces mounting fiscal pressure.

Markets reacted sharply. On Oct. 26, the Ibovespa stock index fell 13.9%, triggering a trading halt, and the dollar rose 8.2% against the real, its largest one-day gain since January 1999.

The decline more than erased the 7.7% rally that followed Bolsonaro's first-round lead, showing how heavily investors had bet on his victory. The reversal does not predict the course of Lula's next government, but its size reflects real doubts about Brazil's public finances.

Those doubts have a basis. In its July review of the Brazilian economy, the International Monetary Fund's Executive Board urged Brazil to reduce spending rigidities and adopt comprehensive spending limits and a binding medium-term debt anchor.

None of this argues for neglecting poverty or social investment, and Brazil's fiscal problems predate Lula's return to office in 2023. Governments of every ideological stripe in the region have learned that spending that outpaces revenue ends in painful adjustment. For the neighbors, the danger is that Brasília's choices make their own stability more expensive to maintain.

Argentina's industrial exposure

The pressure on Argentina runs through its factories. Argentine automakers and parts suppliers depend on production chains integrated with Brazil under Mercosur.

A sustained depreciation of the real against the Argentine peso makes Brazilian goods cheaper on both sides of the border, so Argentine exporters lose ground in Brazil while domestic manufacturers face cheaper imports.

For integrated auto-parts suppliers, any depreciation not offset by productivity gains compresses margins and delays tooling and capacity decisions.

The risk would grow if Brasília responded to economic pressure with local-content requirements, new non-tariff barriers, or more selective use of Mercosur preferences. Politics makes that risk harder to manage.

Milei publicly backed Flávio Bolsonaro by appearing at his party's convention in July, and since August the two countries have been represented only by chargés d'affaires. On Oct. 27, Milei's spokesman said the government would issue no statement on Lula's victory.

Fiscal discipline at home cannot shield Argentina from that combination, and retaliatory restrictions would hurt Argentine firms that rely on Brazilian components. The stronger course is to keep reforming while insisting that Mercosur's commercial commitments hold regardless of how the two presidents regard each other.

Paraguay and the Itaipú tariff

Paraguay's challenge is narrower and potentially more sensitive. It centers on Itaipú, the binational hydroelectric dam whose revenues help fund Paraguayan public investment and social programs.

Under a 2024 agreement, the two countries set the plant's service tariff at $19.28 per kilowatt of contracted capacity per month through 2026, to be followed by a tariff based on operating costs and greater freedom for Paraguay to sell surplus power in Brazil.

That transition is now at hand. Enio Verri, Itaipú's Brazilian director, has projected a tariff of $10 to $12 based on operating costs alone, though the final figure remains open, as does the revision of the treaty's Annex C, which sets the plant's financial and commercial rules.

On Oct. 26, Peña said Lula's reelection could help the talks because Paraguay already knows his team. He aims to close a deal before year-end and insists that Paraguay controls its 50% share of the energy.

The headline tariff is not the whole story. Paraguay's income from Itaipú flows through several channels, including royalties and compensation for energy ceded to Brazil, so a lower tariff would not automatically mean an equivalent loss of revenue.

Cheaper power could also benefit Paraguayan consumers and businesses. The material risk lies in the combined effect of the tariff, the compensation and royalty formulas, and Paraguay's ability to sell its surplus in Brazil under predictable rules.

Brazil has a legitimate interest in competitively priced energy, and a government under fiscal pressure will want it more.

Paraguay's interest lies in an agreement based on transparent calculations and written commercial rights rather than temporary concessions, and in completing the transmission line under construction that Peña says Paraguay needs before it can use its full share of Itaipú's power.

Uruguay's credibility advantage

Uruguay's exposure is broader but less acute. Brazil trails only China as an export market. According to export agency Uruguay XXI, Brazil accounted for 15% of Uruguayan goods exports in the first half of 2026, compared with China's 20%.

A weaker real makes Uruguayan dairy products and manufactured goods costlier for Brazilian buyers and gives Brazilian competitors an edge in third markets.

Orsi's strongest asset is the credibility that distinguishes Uruguay from its larger neighbors, built on stable institutions and a record of honoring international commitments.

That reputation grows more valuable when investors see uncertainty elsewhere, but it cannot neutralize a volatile trading partner. Montevideo's best protection lies in a strong fiscal framework and wider markets beyond the bloc, which would serve as insurance against policy swings in any single market rather than a retreat from regional integration.

Lula's own standard

Brazil's weight in regional trade and investment is unavoidable. The question is whether it operates within predictable rules, and Lula himself supplied the standard. At the Mercosur summit in Asunción on June 30, he said the bloc cannot function according to which president wins each election, or it will never be strong.

Holding Brazil to that principle is the most useful thing its partners can do. Trade commitments and Itaipú's terms should be set down in written agreements, with exceptions limited and justified, so a political quarrel cannot rewrite commercial conditions.

Lula may yet show that social priorities and fiscal responsibility can coexist. Argentina, Paraguay and Uruguay cannot build their strategies on that expectation alone. In an uncertain region, rules that hold are an economic asset, and the neighbors that defend them will be best placed to absorb whatever comes from Brasília.

César Addario Soljancic (www.cesaraddario.com) is an economist specializing in public finance, with decades of experience advising governments and institutions across Latin America and the Caribbean. Over his career, he has led 69 capital-market issuances across 13 countries, totaling nearly $49 billion. The views expressed are solely those of the author.