The main way in which the government regulates Wall Street is through an agency called the Securities and Exchange Commission (SEC). This agency is mainly meant to ensure that the trading on Wall Street is done legally. For example, it is supposed to be sure that no one participates in what is called insider trading, where they use inside knowledge of a company to make good stock deals.
People who want to regulate Wall Street more are generally concerned with regulating the type of trading and/or who does it, not how it is done. They want to do things like banning or regulating credit default swaps to try to make sure that the trading that goes on is less risky.
When government regulates anything this converges into the wider question of freedom liberty and state control.
ways of wall street regulation
Insider trader rules and disclosures
There are whole departments in large companies called Compliance Departments and careers of people who only deal with government regulations on wall street called compliance officers. When I ask my broker to do something special for me he such as buy me tickets to a broadway show he must check with his compliance department to see if it is legal.