BUENOS AIRES, Aug 12 (Reuters) - Argentina's stock, currency and bond market trends on Wednesday.
* MerVal stocks index .MERV rose 0.78 percent to 1,773.29 points following Wall Street after the U.S. Federal Reserve said it saw signs of a more stable economy.
* One of the biggest gainers was market heavyweight Siderar SID.BA. The steelmaker rose 5.48 percent to 15.40 pesos a share after Argentine broker Allaria Ledesma raised its price target on the stock to 22 pesos from 19 pesos, by end 2009. Allaria Ledesma maintained its "buy" recommendation for Siderar.
* On the broad market, volume was moderate at $16.9 million. Of active issues, 54 advanced, 25 declined and 14 were unchanged.
* Prices for government bonds traded over-the-counter in Buenos Aires rose 0.3 percent after an inflation report that some market watchers said showed signs the government is trying to make official data more transparent.
* The dollar-denominated Disc 2033 bond ARDISCD=RASL rose 1.1 percent to end at an ask price of 62.35.
* In formal exchange between banks the peso weakened slightly, by 0.07 percent, to 3.8325/3.8350 per dollar ARS=RASL.
* In informal trade between foreign exchange houses, as measured by Reuters, the peso also weakened 0.19 percent to end at 3.8475/3.8525 ARSB=. (Reporting by Jorge Otaola and Walter Bianchi; Writing by Luis Andres Henao; Editing by Dan Grebler)