The Associated Press

NEW YORK—Wall Street retreated again Friday after readings on jobs and manufacturing—the first reports for the third quarter—indicated that businesses and workers still face a tough economy. The major indexes ended a turbulent week narrowly mixed.

A massive quarterly loss at General Motors Corp. and rising oil prices also gave investors reason to trade cautiously. But the market was considerably calmer than the first four sessions of the week, when the Dow Jones industrials rose or fell by triple digits each day in response to economic data or new...