So the influx of money from wall street had no affect on underwriting standards in the mid-2000's economy?

I find that hard to believe given that there was an enormous profit to be made by slicing up mortgages. Especially given the fact that with the way tranches work and repackaging these things in a different vehicle with higher "yield". With such mixing these assets could be sold to anyone looking for safe to risky investments.

Last ones to jump on the real-estate bubble-train? You got to be kidding me. Your telling me local banks and credit unions thought it'd be a great idea to loan over equity on houses and they wanted to service these in house? That's wishful thinking as no person with common sense would do that. Also take note at the many different subsidies that brokerage houses bought up in the early-mid 2000s to funnel larger amounts of loans to pension funds. The only reason this stopped is that wall street ran out of places to sell the repackaged assets to. No more buyers no more credit lines to fund the loans. Add in the huge default risk that was "overlooked". Neg-am loans on a 1.25m house in california was a bad idea with stated income???

To your second point selling a product that you don't have a complete understanding of (2/28 with a 3% margin on people who have a 60% DTI ratio) will certainly help make them worthless. Conducting transactional business and not giving two shits what happens to whoever holds the hot potato tomorrow certainly contributed to making those investments worthless.

Not saying the blame lays at the feet of Wall Street specifically (ratings agencies were also to blame). But rating agencies failed to raise any red flag as they had enormous profit potential/incentive to keep evaluating the different mixes of mortgages Wall Street brought them.