Wall Street closed out an erratic session with a modest advance Friday as investors awaited further signs about the health of the economy. Falling oil prices and a contract win for Boeing Co. offered some support to a lackluster market, and the major indexes all ended with solid gains for the week.

Energy and materials stocks were weaker Friday, while utilities and financials fared better and generally moved higher. The muted trading followed a sell-off Thursday after Democrats wrested control of Congress from Republicans and touched off concern about sectors from health care to defense.