The decline in Stockholm was broad, with 25 of the 30 most traded stocks in the OMXS30 index in the red.
Of these, defense group Saab fell the most, down 4.4 percent. Mining giant Boliden fell 4 percent after new problems with seismic activity at the mine in Garpenberg.
The industrial group ABB rose the most, up 1.2 percent.
Stock exchanges in Frankfurt, London and Paris also fell. In New York, markets were pointing clearly higher.
Reports of new tensions between the US and Iran around the Persian Gulf have raised concern. The price of a barrel of North Sea oil has risen above $100 again.
Despite the decline in recent days, the Stockholm Stock Exchange rose 0.9 percent during the week.
