LONDON, April 6 (Reuters) - Banking sector turmoil has not dented demand for equities, with MSCI's world stock index up 7% so far this year. But under the surface, bad omens for world stocks are building. Central bank surveys show U.S. and European banks are already tightening lending standards, historically a predictor of dismal stock market performance. Credit tightening predicts poor stock market returns2/ MANUFACTURING SLOWDOWNRecessions starting in the United States tend to flow to the rest of the world and consequently global stocks. Seven mega-cap tech stocks were responsible for 92% of the S&P 500's first-quarter rise, Citi notes.

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