Monthly GDP rose 1.0% in September following a 0.6% increase in August (unrevised). The increase in September reflected gains in personal consumption expenditures, nonfarm inventory investment, net exports, and residential investment that were partially offset by declines in the portion of government spending we track with monthly source data and the portion of monthly GDP not covered by the monthly source data. The level of GDP in September was 3.3% above the third-quarter average at an annual rate. Implicit in our latest tracking forecast of 5.1% annualized GDP growth in the fourth quarter are increases in monthly GDP averaging 0.3% per month over the three months of the fourth quarter.

Our index of Monthly GDP (MGDP) is a monthly indicator of real aggregate output that is conceptually consistent with real Gross Domestic Product (GDP) in the National Income and Product Accounts. The Monthly GDP Index is consistent with the NIPAs for two reasons: first, MGDP is calculated using much of the same underlying monthly source data that is used in the calculation of GDP. Second, the method of aggregation to arrive at MGDP is similar to that for official GDP. Growth of MGDP at the monthly frequency is determined primarily by movements in the underlying monthly source data, and growth of MGDP at the quarterly frequency is nearly identical to growth of real GDP.

Posted 03 November 2020 by Ben Herzon, US Economist, Insights and Analysis, S&P Global Market Intelligence and

Kathleen Navin, Economics Executive Director, US Macroeconomics, S&P Global Market Intelligence