In the United States, the firm ??? which makes most of its prof??its by man??ag??ing money for investors, pen??sion funds, endow??ments and other insti??tu??tions ??? has been crit??i??cized for buy??ing and sell??ing some of the same secu??ri??ties that its Black??Rock Solu??tions unit is valu??ing for the gov??ern??ment.