The job market is strong. So why did layoffs double in January?

The job market remains one of the U.S. economy's main engines, with the nation's unemployment rate near a 50-year low and wages finally pulling ahead of inflation. At the same time, major companies in technology, finance, media and other key sectors have all recently announced sizable job cuts, with layoffs nationwide more than doubling in January from a month earlier.

U.S. companies in January announced more than 82,300 job cuts, a 136% increase from December, according to a new analysis from executive coaching firm Challenger, Gray & Christmas. 

That may raise questions about the strength of the labor market as well as concerns among employees about their job security. On Friday, new government data is expected to show that businesses hired about 177,000 workers, with the jobless rate ticking up slightly to 3.8% from 3.7% in December, according to economists polled by FactSet.