"Sens. Pat Toomey (R. Pa.) and Ron Johnson (R. Wis.) asked the Federal Retirement Thrift Investment Board, which oversees the government's $760 billion Thrift Savings Plan, to detail how [BlackRock Inc. and State Street Global Advisors] cast proxy votes over everything from who sits on corporate boards to executive pay and priorities at companies. They have also requested past communications with the firms and other information to determine whether the asset managers voted in ways that violated their responsibilities to those in the savings plan."