Corporate America's cash pile has hit its highest level in half a century.

Rather than pouring their money into building plants or hiring workers, nonfinancial companies in the U.S. were sitting on $1.93 trillion in cash and other liquid assets at the end of September, up from $1.8 trillion at the end of June, the Federal Reserve said Thursday. Cash accounted for 7.4% of the companies' total assets—the largest share since 1959.

The...