BUENOS AIRES, April 15 (Reuters) - Argentina's stock, currency and bond market trends on Wednesday:
* The MerVal stocks index .MERV edged 0.7 percent higher to 1,214.92 points, tracking volatility on Wall Street a day ahead of bimonthly options expiries.
* Tenaris (TENA.BA), which makes steel pipes for the energy industry and is weighted as almost half of the MerVal, gained 1.86 percent to 43.85 pesos per share.
* On the broader market, stock volume was weak at $12.7 million. Of active issues 51 advanced, 20 declined and 19 were unchanged.
* Prices for government bonds traded over the counter in Buenos Aires gained an average 0.3 percent in thin trade. They have risen nearly 9.5 percent since the start of April.
* Peso-denominated 2033 Discount bonds ARDISCP=RASL jumped 3.3 percent, according to the ask price.
* In formal exchange between banks, the peso firmed 0.07 percent to 3.6750/3.6775 per dollar ARS=RASL. The central bank intervenes nearly every day in this market to avert abrupt movements.
* In informal trade between foreign exchange houses as measured by Reuters, the peso weakened 0.2 percent to 3.72/3.7225 ARSB=.