March 9, 2014, 3:00 p.m. EDT Stock caution urged as margin debt levels hit new highs P/E valuations, record highs flash warnings; stock pickers look for quality, value SAN FRANCISCO (MarketWatch) — A number of warning signals are flashing in the stock market, and while not indicative of an imminent crash, they’re telling investors to exercise caution, say market strategists. Stocks finished higher last week, ending on a choppy Friday highlighted by the release of a better-than-expected job report. The Dow Jones Industrial Average advanced 0.8%, the S&P 500 Index rose 1% to close at another record high of 1,878.04,...