The first federal government shutdown in 17 years, triggered by a Republican demand to defund the Affordable Care Act on Oct. 1, cost the U.S. $24 billion in potential economic activity — equalling at least 0.6% of projected annualized fourth-quarter 2013 GDP growth, according to ratings agency Standard & Poor’s.

Instead of the 3% annualized growth fourth quarter originally projected in September, S&P now forecasts actual fourth-quarter growth near 2%, the agency said in a press release: