The U.S. economy expanded at a 4.1% annual rate in the third quarter, the strongest since the final three months of 2011 and up from an estimate of 3.6%, the Commerce Department said Dec. 20.

Economists' forecasts for gross domestic product ranged from gains of 3.3% to 3.8%, Bloomberg News reported.

Inventories accounted for a third of the gain in GDP, showing companies were confident about the prospects for demand, Bloomberg said.

Business inventories increased at a $115.7 billion annual rate in the third quarter, the most in three years, after a previously reported $116.5 billion annual rate, Commerce said.

GDP measures the value of all goods and services produced.

“You have equity markets supporting household net worth, rising home values and also payroll gains and falling unemployment, so we do really look for consumption to start picking up,” Robert Rosener, associate economist at Credit Agricole CIB, told Bloomberg.