The crowding out effect is when government issued debt drives down private sector spending.

The U.S. Treasury sells IOUs in the form of bonds or treasury bills directly to the private capital markets and uses the proceeds of the sales to finance the deficit.


The US Treasury is competing directly in the capital markets with private corporations, which may also be seeking to sell bonds and stocks to raise money to invest in new plant equipment. To compete for these scarce investment dollars, the Treasury typically must increase the interest rate it is offering to attract enough funds. Running a huge deficit is largely a zero sum game because funds to finance the deficit would otherwise be spent on private sector investment (the I variable in the GDP formula).

Money used to finance the deficit is money that would otherwise have been borrowed and spent by corporations and businesses on private investment. Deficit spending by the government is said to crowd out private investment. Crowding out is the offsetting effect on private expenditures caused by the government’s sale of bonds to finance the deficit. The larger the deficit and the more government needs to spend on financing that deficit, the more crowding out occurs.

The crowding out effect, which is one of the most important concepts in macroeconomics, is illustrated below.


The initial equilibrium is at Y, where the aggregate expenditure curve AE, crosses the aggregate production curve AP. However, expansionary fiscal policy shifts the aggregated expenditure curve up to AE1. This leads to a new equilibrium of Y1. However, because the government has had to borrow money from the private capital markets to finance these expenditures, interest rates rise. This reduces investment and a resulting contractionary effect shifts the aggregate expenditure curve back down from AE1 to AE2.


The final equilibrium is now at Y2 as the net economic expansion equals Y2 minus Y. At the same time, the partial crowding out of private investment may be measured by Y1 minus Y2. The level of partial crowding out rises the more government borrows from the private sector.

It is my opinion that government deficits are a weak fiscal policy tool at best, and I think the eight years of President Obama increasing the national debt and running the largest deficits in US history has proven that point.

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