Why Thursday’s U.S. CPI report might kill stock market’s hope of inflation melting away

A mild stock market rally to kick off the new year will be put to the test Thursday when investors face a highly-awaited U.S. inflation reading which could well help determine the size of the Federal Reserve’s next interest-rate increase.

The December CPI reading from the Bureau of Labor Statistics, which tracks changes in the prices paid by consumers for goods and services, is expected to show a 6.5% rise from a year earlier, slowing from a 7.1% year-over-year rise seen in the previous month, according to a survey of...