For the first time this week, Wells Fargo ( NYSE:  WFC ) stock has dipped below the $40 mark, despite some  good news on the housing front . Not that Wells is alone:  Bank of America ( NYSE:  BAC ) ,  JPMorgan Chase ( NYSE:  JPM ) , and  Citigroup ( NYSE:  C ) are all down this Friday morning, as are both the  S&P 500 and the  Dow . What's going on here?

Wells and JPMorgan lose out to Fannie
As far as crummy news goes, the revelation that Fannie Mae has been squeezing JPMorgan and Wells out of some juicy profits is pretty bad. The government-sponsored enterprise has been cutting both banks out of a rather lucrative loop, the business of securitizing home mortgage debt for investors. As the heaviest hitters in the home loan origination market, both Wells and JPMorgan stand to lose the biggest piece of that profitable pie.

But, that doesn't explain why Citigroup is falling further than Wells -- but this tidbit might. According to  The New York Times , banks are having their lobbyists participate in writing banking laws directly, without bothering those busy congresspersons with all of the usual yammering. One of the most recent of these lobbyist-crafted bills to pass muster was by Citigroup, and it will save oodles of trades from pesky new rules meant to rein them in.

As for B of A, its lethar…