Currency dealers said the government-run Banco do Brasil sold dollars to prop up the currency, the real, which closed at 1.72 to the dollar, compared with 1.70 on Thursday. Before the devaluation, a dollar bought just 1.21 reals.

The Central Bank declined to comment on reports it had sold dollars through Banco do Brasil. But little else would explain the strengthening of the real after it opened down sharply at 1.75 Friday morning.

The real had fallen about 30 percent since last week, when the Central Bank stopped spending dollars to support its value. Bank President Francisco Lopes said the monetary authority would allow the real to float but might step in to avoid exaggerated swings.

The steadier real also helped calm the Sao Paulo stock exchange, Latin America's largest. The exchange's Bovespa index declined 2.3 percent in trading Friday. On Thursday, jitters over the plunging real sent the Bovespa down by 4.6 percent after a euphoric 52-percent rise the four previous days.

The real's decline and the continued outflow of dollars — more than $1.7 billion since the devaluations began Jan. 12 — are seen as a sign that the financial crisis here could deepen.

The turmoil in Latin America's largest economy has raised fears that it could spread across the continent and even affect the United States.

On Friday, Lopes met with Finance Minister Pedro Malan and said the government has no plans to restrict capital outflows. Markets estimate that Brazil's currency reserves have fallen to less than $30 billion, not including the $9 billion Brazil received under a $41.5 billion aid package from international lenders.