.0 million of collateral under these contracts . if the credit-risk-related contingent features underlying these agreements had been triggered on may 31 , 2015 , we would have been required to post $ 56.5 million of collateral to counterparties . concentrations of credit and counterparty credit risk during fi scal 2015 , wal-mart stores , inc . and its affi li- ates ( wal-mart ) accounted for 21 percent of our consol- idated net sales and 30 percent of our net sales in the u.s . retail segment