Measuring net output GDP in a specific year

Question

Why do national income accountants comprise only final goods in measuring net output GDP in a specific year? Why don't they comprise the value of stocks and bonds bought & sold? Why don't they comprise the value of utilized furniture bought and sold?

Answer 1

They are excluded since the dollar value of ultimate goods includes the dollar value of intermediate goods. If intermediate goods were counted, then multiple counting would take place. The value of steel (intermediate good) utilized in autos is included in the price of the auto (the final product).

     This value is not comprised in GDP since such sales and purchases simply transfer the ownership of existing assets; such purchases and sales are not themselves (economic) investment and therefore should not be counted as production of ultimate goods and services.

     Utilized furniture was generated in some previous year; it was counted as GDP then. Its resale does not measure new production.