In 1999, Phil Gramm introduced in the Senate what eventually became known as Gramm-Leach-Bliley Financial Services Modernization Act which, to quote from wikipedia, "...removed Depression-era laws separating banking, insurance and brokerage activities..."
In 2000, he helped sponsor the Commodity Futures Modernization Act of 2000 which contained the infamous Enron Loophole.
These two Acts of legislation effectively deregulated most financial activities. Banks could function as brokers as well as provide themselves mortgage insurance. They could speculate in energy. I point out that both Acts received many modifications from other members of congress between the time the Acts were introduced and they were passed.
Phil has left the Senate. He's now a lobbyist. Or was until he became John McCain's presidential campaign co-chair and main economic adviser. Amid controversy, he recently stepped down from that position after he made the comments: "...'You've heard of mental depression; this is a mental recession,' and 'We have sort of become a nation of whiners, you just hear this constant whining, complaining about a loss of competitiveness, America in decline.'..." I quote from wikipedia again. Phil is still seen publicly with John McCain and continues as an economic adviser.