The “Plunge Protection Team” is the colloquial name for the Working Group on Financial Markets (WGFM). The Working Group was established by the executive order of President Reagan in 1988, in the aftermath of the stock market plunge of October, 1987.
The group reports to the President, and the official members of the group include the Secretary of the Treasury, the chairman of the Federal Reserve, the chairman of the SEC, and the chairman of the CFTC. In other words, the group members are the four most powerful financial officials in the United States. In practice, the committee can be composed of senior aides and officials that have been designated by those top officials.