 Shares of EPAM Systems Inc. EPAM, -13.39 tumbled 11.7 toward an 11-month low in morning trading Thursday, enough to pace the SP 500s SPX, -1.62 decliners, as Russias invasion of Ukraine weighed on provider of digital platform engineering services. The stock is headed for the biggest one-day percentage selloff since it plunged 16.6 on March 16, 2020. 