Stocks managed a mixed start Tuesday as DuPont (DD) almost single-handedly hoisted the Dow into positive territory. The Dow Jones industrial average climbed 0.4%. The S&P 500 reversed out of early losses to a 0.1% gain. The Nasdaq remained down 0.2%, with Illumina (ILMN) pulling hard to the downside. Volume was mixed, up 14% on the Nasdaq and 13% lower on the NYSE, vs. action at the same time Monday.