NEW YORK—Stocks advanced for the second straight session Wednesday as another decline in oil prices and several upbeat profit reports eased some of Wall Street’s concerns about the economy.

Investors expect that a sustained pullback in oil prices would give a crucial boost to the economy. Crude has retreated as oil investors have worried that high prices and a sluggish economy are reducing demand. The government reported Wednesday that domestic inventories increased last week as consumers curbed their energy use.

Oil is down more than $20 a barrel since hitting a record...