The quarterly decline was the worst in modern history, topping the 3.8% drop in fourth quarter in 2008, during the financial crisis. But the Swedish economy out-performed much of the rest of Europe's.
Second-quarter GDP in the euro zone fell 12.1% from the previous period and 11.9% across the whole of the European Union. The German economy contracted 10.1%, the Spanish economy by 18.5% and the Italian by 12.4%.
"The economic crunch over the first half of the year is in a different league entirely to the horror shows elsewhere in Europe," David Oxley, senior Europe economist at Capital Economics, said in a note.
Sweden's response to the COVID-19 outbreak has differed from most other countries in Europe, relying mainly on voluntary measures.
Most schools and many businesses have remained open and, although economic activity has been badly hit, many analysts had forecast that the slump would not be as bad as in many countries that adopted more drastic lockdown measures.
The banking group SEB had forecast a quarterly fall of 8% from the previous period. Nordea had predicted a decline of 8.5%. The central bank foresaw a drop of 8.8%.
(Reporting by Stockholm Newsroom; editing by Larry King)
