(Updates with closing prices)
BUENOS AIRES, Dec 1 (Reuters) - Argentine stocks and bonds fell on Monday, breaking a run of five consecutive gains due to heavy losses on Wall Street and growing fears of a global recession.
The MerVal index .MERV of leading stocks closed down 6.9 percent to 925.18 points -- its biggest one-day loss since Oct. 24. In the previous five sessions, the index had risen 19.9 percent.
"The sharp losses in international markets set the tone for the MerVal," said Marcelo Trovato, a trader at the Caja Social brokerage.
Among the day's biggest losers was Petrobras APBR.BA (PETR4.SA), Brazil's state-run energy company, which fell 12.3 percent to 32 pesos per share.
On the broad market, volume was thin at $16.6 million.
Meanwhile, locally traded government bonds fell 0.7 percent on average in over-the-counter trade, also ending a run of five straight gains in which they rose 11.3 percent.
Traders said the slide in global stock markets and profit-taking sent prices lower after initial gains.
On the foreign exchange market, the peso weakened 0.22 percent against the dollar to 3.38/3.825 ARS=RASL in formal interbank trade, pressured by private demand for safe-haven greenbacks despite dollar sales by the central bank, traders said.
However, the currency firmed by the same margin to 3.4025/3.4075 per dollar ARSB= in informal trade between foreign exchange houses, as measured by Reuters.
The central bank intervenes in the foreign exchange market on an almost daily basis. (Reporting by Jorge Otaola; Writing by Helen Popper; Editing by Leslie Adler)