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SAO PAULO, Oct 30 (Reuters) - Brazilian stocks tumbled on Friday, as mixed economic data in the United States worried investors about the strength and breadth of a global economic recovery and scared them off riskier emerging market assets.

Sao Paulo's Bovespa index .BVSP sank 3.41 percent to 61,545.50, just about zeroing out the index's gains for the month of October.

Friday's loss posed a stark contrast to Thursday's nearly 6-percent rally after data then showed the United States returned to growth in the third quarter.

But data on Friday suggested that the recovery in the United States, the world's largest economy, was rocky. Strong Midwest area manufacturing was balanced against a slip in consumer sentiment this month. [ID:nN30412996] [ID:nLU357472]

Investors sold off riskier emerging market assets as a result, with Brazil's currency, the real (BRBY: Quote, Profile, Research), weakening 1.4 percent to 1.756 per dollar. The greenback, considered a safe haven in times of economic uncertainty, gained against a basket of major currencies .DXY.

Shaken investors sent U.S. stocks lower, too, as the Dow Jones industrial average .DJI shed 2.5 percent.

Because the United States is the world's largest economy, its financial health affects financial decisions taken across the world.

"The biggest worry for markets today is still on what's going on abroad," said Eduardo Cotrim, Treasury desk director at Banco Modal.