31 C.F.R. § 129.1
The purpose of this part is to provide general information on portfolio investment survey data collection programs and analyses under the International Investment and Trade in Services Survey Act ((formerly the International Investment Survey Act of 1976) (the "Act")). The purpose of the Act is to provide for the collection of comprehensive and reliable information concerning international investment, including portfolio investment. The Act specifies that regular data collection programs and surveys specified by the Act or deemed necessary by the Secretary of the Treasury shall be conducted to secure information on international capital flows and other information related to international portfolio investment, including information that may be necessary for computing and analyzing the United States balance of payments.
31 C.F.R. § 129.1