The sliding dollar has been a big reason why US stocks have rallied this year. But companies with strong foreign sales—which benefit most from the weak dollar—have had the biggest gains by far.

Stocks skidded Tuesday after a report showed consumer confidence is waning amid worries about the job market. It was a struggle all morning as investors juggled another batch of disappointing earnings results against an encouraging report on the housing market.

Stock futures drifted slightly lower ahead of the open Tuesday as investors waited for the next batch of earnings and key economic data.