BY FRANCESCO GUERRERA

Here are a couple of phrases a bank investor or executive doesn't want to hear: "What sort of [profit] do you need today?" And: "We should mark these [positions] down because someone is going to spot this."

Those words, from traders at Credit Suisse Group AG during the credit crunch, epitomize the mindset that gave Wall Street a starring role in the drama of 2007-2008. They also highlight key shortcomings in the financial system that still need to be fixed.

The alleged actions that accompanied those utterances—inflating the prices of mortgage bonds as the market was cratering—led to criminal charges ...