I think it important to distinguish between a free trade market, which should be largely unregulated. People should be able to buy and sell goods on an open market.
Capital markets, or ownership and control of wealth should be heavily regulated.
Derivatives should be outlawed and stock trading should have minimum asset holding periods of 24 months or more. Return it to a platform for making investments and raising capital, rather than a gambling and market manipulation platform.
I would also change the law that the duties of publicly traded company's board and executives is not profit, but the long term sustainability of the organization.