If the gears continue grinding the way they are right now, it looks like the U.S. government is set to shut down for the first time since 1995. If you're a shareholder of Bank of America (BAC 0.82%) does that mean it's time to freak out?

The short answer: no. Of course that's partly because when it comes to investing, freaking out is never the right answer.

There are, however, some reasons to potentially be concerned. Let's take a quick look at a few of them.

B of A's debt portfolio
One of the potential threats from a government shutdown is another downgrade of the U.S.'s credit rating. If ratings agencies become even more convinced that the government's purse strings are controlled by a bunch of squabbling middle-schoolers, it may make sense to them to signal a higher credit risk.

History tells us that this isn't necessarily terrible for holders of government debt. In fact, history tells us it could be good -- when Standard & Poor's last downgraded the U.S. debt rating, Treasuries surged.

Even so, B of A has hundreds of billions of dollars in securities on its balance sheet -- largely agency-backed paper -- that stand to be affected by a downgrade.

The real estate market
Not surprisingly, there's been a bit of confusion around what government services will be up and running in a shutdown scenario. One that appears will be chugging forward is the Federal Housing Administration (FHA) -- at least as far as its ability to endorse single-family loans.

Fannie Mae (FNMA -1.44%) and Freddie Mac (FMCC -2.21%) will also be operational if the government shuts down, since they're off on their own little island.

In other words, there's no reason to expect the real estate market -- which has plenty of government involvement -- will come to any sort of a screeching halt if the government kills the lights. But that's also not to say that everything will be as usual. The confusion that would ensue would almost certainly send many buyers to the sidelines with a "wait and see" approach.

The U.S. economy
Bank of America is heavily hitched to the U.S. economy, and a government shutdown would do no favors for an economic recovery that is deemed even by the optimists (like me) as tepid.

As I noted above with the real estate market, confusion would be a paramount issue. As long as businesses and consumers have to wait and wonder what the shutdown means, how long it will last, and what the eventual outcome will be, it's all the more likely they are to put off any major spending decisions. 

Even more direct is the government spending that won't happen if it shuts down and the blow-back from furloughing nearly 800,000 government workers.

Big picture
None of this is particularly promising, and this Fool views the partisan bickering going on as... well, let's just say distasteful. 

But from a long-term investment perspective for Bank of America, most of the picture doesn't really change. The bank still needs to continue handling and moving past its big legal liabilities. It needs to ratchet down the cost bloat that stemmed from the crisis. And it needs to find ways to connect more effectively with customers and get growth back on track.

In other words, investors need not get too distracted with what should be a short-term issue. And while I've focused on Bank of America here, the same holds true for the other U.S. megabanks. Wells Fargo (WFC 0.31%) and JPMorgan (JPM 0.74%) have large debt portfolios that have some of the same downgrade risk as B of A's. Both also arguably have even more exposure to short-term real estate hiccups, particularly as it pertains to origination fee income.

Citigroup (C 1.04%) has some of the same exposures, but it may stand to be the most sheltered of the four thanks to its broad geographic exposure. But that's not to say Citi investors should be rooting for a shutdown.