A member of the Third U.S. Infantry Regiment (The Old Guard) carries flags during a "Flags-In" ceremony at Arlington National Cemetery in Washington May 22, 2014. REUTERS/Kevin Lamarque Economists estimated U.S. GDP contracted in the first quarter, but not by this much.

According to the Bureau of Economic Analysis, GDP fell 2.9% at an annualized rate in Q1. This third estimate was down sharply from the BEA's previous estimate of -1.0%.

This was also much worse than the -1.8% forecast by economists.

As expected, healthcare spending was revised down sharply. It went from adding 1.01 percentage points to subtracting 0.16 from the headline GDP growth number.

"It marked the second biggest downward revision from the agency's second GDP estimate since records began in 1976," reported Bloomberg's Jeanna Smialek.

From the BEA: "The decrease in real GDP in the first quarter primarily reflected negative contributions from private inventory investment, exports, state and local government spending, nonresidential fixed investment, and residential fixed investment that were partly offset by a positive contribution from PCE. Imports, which are a subtraction in the calculation of GDP, increased."

Personal-consumption growth was slashed to 1.0% from 2.4%.

The buildup in inventories subtracted 1.7 percentage points from GDP.

Real final sales, or GDP less the change in private inventories, was revised to -1.3%. That's down from +0.6% a month ago. It was +2.7% in Q4.

Here's a breakdown of GDP components via BEA: