U.S. Markets: The major U.S. indexes retreated as investors reacted to bleak economic data and multiple warnings of further weakness ahead.  The declines were most pronounced in small-caps and slower-growing value stocks.  Health care and consumer shares held up relatively well, while energy stocks lagged despite a rise in oil prices. The Dow Jones Industrial Average declined 646 points to finish the week at 23,685—a decline of -2.7%.  The [...]