Nothing really defined in advance the things they were doing wrong.
The financial collapse, from start to finish, is an excellent example of why trying to reform or crusade against Wall Street a priori is pointless. Because this was all due to incompetent government by ideologues once the G.W. Bush crowd moved into the executive branch.
The problems all arose from incompetent and lax oversight from the people in government whose job it is to manage securities products, the money supply and business practices. I.e. G.W. Bush got into office and he was jejeune, naive and clueless. He was a great icon for evangelicals, but he was a bad manager of the business of government. He appointed clueless people to important positions. While bad mortgage securities were being crafted, obviously, there was no law against them because those derivative products that created risk tranches were new and had never been seen before. The SEC ignored a lot of problems and warnings and obvious signs of bubble type products and spent their time getting splashy headlines trying to bring down Martha Stewart, a prominent liberal donor, on novel insider trading accusations. A low interest rate was helping the Federal Reserve prop up the stock market post tech bubble and this fed the liquidity bubble. The list of shitty executive branch and government fumbles is really extensive.
I could go on and on but what my point is that G.W. Bush and his neocon team moved into what was essentially the same framework and environment that the Clintons had thrived in and had run the country so well in, and in a few short years demolished it all, and the prosperity, with the most irresponsible, incompetent and haphazard bumbling. He also definitely undermined federal regulatory offices already in place, and replaced career civil servants with people who undermined their agencies.
Bush was a popular, charismatic and evangelical guy who had strong appeal for the right wing base but a shallow resume. He basically screwed up the whole country from at the nuts and bolts level from to the top down with his poor governance. This is why it was such a relief in 2008, for many of us, that Hillary Clinton ran to replace him and why it was so frustrating when the progressives forced someone who was essentially a Black Bush -- charismatic, strong base appeal but thin resume -- into the primary season and turned the Democrats into the party of identity politics from being the party of good government. Which it has been since.
We don't need to formulate laws that are so stringent they cover every possible new securities product that the banking industry might come up with. We just have to stop electing entertaining ideologues because they appeal to the crusader side of us and go back to electing people who are experienced, smart and dedicated enough that they can run government well without destroying the country.