By Taos Turner 
 

BUENOS AIRES--Argentine stocks fell in tandem with declines on Wall Street Thursday while the peso weakened against the U.S. dollar.

The Merval stock index slid 0.46% to 3,865.11 in unusually high-volume trade totaling ARS111 million ($19.8 million).

The most traded stock was the financial conglomerate Grupo Financiero Galicia (GGAL, GGAL.BA), which bucked the trend, slightly, and rose a hair to ARS5.79. Steel producer Tenaris SA (TEN.MI, TS) slid almost 1% to close at ARS196.25. Its sister company, Siderar SAIC (ERAR.BA), fell 3.5% to ARS2.44.

Argentina's GDP warrants--or securities whose performance is tied to economic growth--were mixed. The TVPP warrant fell 0.72% in price terms to ARS9.68, while the TVPA rose 1.33% to ARS76.

The Argentine peso weakened to ARS5.5670 against the dollar on the regulated MAE foreign-exchange wholesale market, compared with ARS5.5520 the previous session.

The central bank intervenes in the exchange market on an almost daily basis to buy dollars and build its foreign currency reserves, while gradually weakening the peso to help exporters.

In the underground market, the peso was quoted at ARS9.05, compared to ARS8.84 the previous session, according to the newspaper El Cronista, which publishes rates collected from black-market traders.

Strict capital controls that limit the amount of foreign currency Argentines can purchase legally have fueled a parallel illegal market for dollars where people pay a steep premium for the U.S. currency.

Write to Taos Turner at taos.turner@wsj.com