BUENOS AIRES, July 29 (Reuters) - Argentina's stock, currency and bond market trends on Wednesday:
* The MerVal stocks index .MERV fell 0.57 percent to 1,655.68 points, tracking losses in foreign markets as global prices for raw materials such as oil dropped.
* Buenos Aires-listed shares of Brazil's state-run energy company Petrobras APBR.BA fell 2.77 percent to 77.3 pesos per share.
* On the broader market, volume hit $9.1 million. Among active issues, 40 declined, 24 advanced and 12 were unchanged.
* Prices for government bonds traded over-the-counter in Buenos Aires inched up 0.2 percent on average. Traders said the recent rally in Argentine bonds might start to ease as expectations over the country's fiscal position deteriorate.
* Bonds have been rising since last week, when the economy minister said he would seek to swap and buy back the inflation-indexed bonds that account for at least a third of the country's sovereign debt.
* The peso-denominated Discount bond was among the day's winners, climbing 1.6 percent ARDISCP=RASL to an ask price of 90.80.
* In formal trade between banks, the peso fell 0.13 percent to 3.8175/3.82 per dollar ARS=RASL as the greenback's appeal as a safe haven rose.
* In informal trade between foreign exchange houses as measured by Reuters, the peso edged down 0.06 percent to 3.86/3.865 per dollar ARSB=. (Reporting by Walter Bianchi; Writing by Dana Ford)