Stocks appeared set for a second straight loss Wednesday after weaker-than-expected jobs data raised concerns about Friday’s key nonfarm payrolls report. The Dow Jones industrial average was down 0.7%, the S&P 500 shed 0.6% and the Nasdaq slipped 0.3%. All cut early losses by more than half. Volume was mixed, up 4% on the NYSE and down 8% on the Nasdaq compared with the same time Tuesday.