The European sovereign debt crisis may hit already-tepid growth which US investment bank Morgan Stanley had forecast at 1.2% in 2010. Data last week showing Q4 2009 expansion at 0.1% and a poor start to the current quarter, mainly related to very bad weather, underscore the downside risks and the impact of even dramatically slower growth in Europe would only trim US growth fractionally; Asia is far more important for the US outlook However, Morgan Stanley's top economist, Richard Berner, says the debt crisis does create a tail risk for US growth and markets: If the crisis spills over into broader risk-aversion and a drying up of liquidity - the functional equivalent of the US subprime crisis - the consequences could be more dire.  At the least, these unknown risks make MS more cautious about risky assets.