Entire fields of finance exist for this. Find the hole in the model, and stuff billions of bonds and derivs in it. This is especially an issue when the model

Entire fields of finance exist for this. Find the hole in the model, and stuff billions of bonds and derivs in it. This is especially an issue when the model sellers optimize off of it. Also a reason why it's good to be leery when people say, "I don't need to know what's going on in the model, the results are good enough."