The government shuts down. The economy unravels. Stocks plunge.
That may be Wall Street's worst fear, but history shows it's mostly overblown.
There have been 17 government shutdowns since 1976, ranging in length from one to 21 days. None has caused a market meltdown.
The average decline in the Standard & Poor's 500 index during a shutdown lasting 10 days or more is about 2.5 percent. For shutdowns lasting five days or fewer, the average decline is 1.4 percent.
"If they shut the government down for two days, the world's not going to stop revolving," says Ron Florance, deputy chief investment officer for Wells Fargo Private Bank.
Shutdowns may even offer a buying opportunity.
Investors should consider the improving outlook for the global economy instead of worrying about Washington.
This isn't August 2011, when the government hit the debt ceiling and the Dow Jones industrial average endured three weeks of triple-digit swings. Europe's economies are no longer is crisis and the U.S. recovery is farther along.
In fact, stocks rose 6.5 percent in the first three months of 2013 heading into the most recent government "crisis," the start of the automatic federal budget cuts, also referred to as the sequester.
(Read more: Why markets shouldpray for a government shutdown)
Still, investors this week have been warily eyeing Washington's budget negotiations. If a budget fails to pass, a government shutdown could start as soon as Tuesday. The stock market has fallen six of the past seven trading days. While the two percent decline over that stretch is modest, it shows that investors have been leery of buying stocks ahead of two big financial deadlines for U.S. government.