Stocks plunge one day after Obama re-election

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Wall Street pros said negative sentiment was amplified Wednesday after European Central Bank President Mario Draghi expressed concerns ahead of the U.S. market open about the outlook for Europe's economies, especially Germany.

Others said much of the sell-off is coming from computerized trading programs, which trigger huge sell-offs of stocks when certain price levels are hit versus investors who are making decisions in the moment based on changes about what they think of the outlook for stocks.