Two Groups of Stocks Are About to Send Crisis-Era Signals on the Economy

The S&P 500 is at a record, but areas of the stock market with a reputation for economic prescience are sending warning signals that hearken to the global financial crisis.

It’s small caps and transportation stocks, whose performance has deteriorated at a much faster clip than other parts of the market. Relative to the S&P 500, each group is on the brink of hitting its lowest point since 2009. For investors, the decline is another example of the growth debate churning underneath the market’s surface.