Brazil stocks sink 6 pct as U.S. markets tumble

SAO PAULO, Nov 5 (Reuters) - Brazil's benchmark stock index fell 6 percent in afternoon trading on Wednesday as a slump on Wall Street weighed on mining company Vale, state-run Petrobras and other widely traded shares.

The Bovespa index .BVSP of the Sao Paulo stock exchange plunged as low as 37,838.99, reversing course after a two-day surge that pushed the index 8 percent higher.

U.S. markets sank, with the Dow Jones industrial average .DJI and the Nasdaq Composite index .IXIC both falling more than 3 percent, prompting investors to cut exposure to riskier emerging market assets.

Petrobras (PETR4.SA) lost 3.2 percent, while Vale (VALE5.SA) was down 5.6 percent, weighed down by a slump in crude oil, copper and other industrial metals prices.

Itau, Unibanco and other banking stocks also declined, after rallying the past two days on hopes of consolidation in the financial services sector. Itau ITAU4.SA sank 9.4 percent and Unibanco UBBR11.SA was down 11.4 percent, while Bradesco (BBDC4.SA) dropped 7.4 percent. (Reporting by Elzio Barreto; Editing by James Dalgleish)