Stocks are sexy, but bonds are the most important market in the world

The bond market is growing more interesting lately — and that's concerning.

Why it matters: The $160 trillion global bond market is like the plumbing in your house. You don't think about it until it stops working and you've got a nasty situation on your hands.

The big picture: Long-term government bond yields for the U.S. and other G7 countries have been climbing — hovering at levels last seen in 2007 before the financial crisis — and raising concerns about borrowing costs growing more expensive for countries that are already staring down heavy debt loads...