Markets are weak despite strong returns. Plus: stock picks, bond investing advice and the world's new most valuable company

I'm going to recount one of legendary Merrill Lynch strategist Bob Farrell's 10 Market Rules to Remember for the second time this month because it's too topical to avoid. Mr. Farrell's rule number seven is "Markets are strongest when they are broad, and weakest when they narrow to a handful of blue-chip names." From this perspective, U.S. markets are currently extremely fragile. Morgan Stanley Wealth Management chief investment officer Lisa Shalett reported this week that by one measure, using the S&P 500 Equal Weight Index, the current market is more narrow than at any time since the year 2000 when…