BUENOS AIRES, Aug 20 (Reuters) - Argentina's stock, currency and bond market trends on Thursday.
* MerVal stocks index .MERV rose 2.23 percent to 1,766.89 points due to investor optimism over a government debt swap plan and an equity rebound in China.
* Among the biggest gainers was Banco Macro BMA.BA, which rose 8.7 percent to end at 7.12 pesos per share. Argentine banks hold large quantities of government bonds, meaning their stock rises when debt prices climb.
* On the broad market stocks volume was moderate at $16.4 million. Of active issues 45 advanced, 19 declined and 12 were unchanged.
* Prices for government bonds traded over-the-counter in Buenos Aires rose 1.4 percent due to optimism over a government plan to exchange inflation-indexed bonds in the coming weeks for others that will pay the local Badlar rateBCRA18 "plus a few points."
* The dollar-denominated Disc 2033 ARDISCD=RASL rose 2.6 percent to an ask price of 63.00.
* In formal exchange between banks the peso stayed flat at 3.8475/3.8500 per dollar ARS=RASL.
* In informal trade between foreign exchange houses, as measured by Reuters, the peso weakened slightly by 0.06 percent to end at 3.88/3.885 ARSB=. (Reporting by Walter Bianchi, writing by Luis Andres Henao; Editing by Leslie Adler)