The broad OMXS-index fell 1.1 percent on Thursday, while the OMXS30-index with the most traded shares dropped 1.4 percent. Among the major companies, only the cloud service company Sinch closed on a plus, up 0.7 percent.
The indexes were weighed down by a decline in the clothing giant H&M. The share fell 4.5 percent after a lowered recommendation from analysts.
An even bigger loser was Saab. Like many competitors around Europe, the defense conglomerate's share dropped after reports emerged that Ukraine is considering alternative peace plans. Saab lost 5.7 percent.
The indexes on the leading European stock exchanges also fell, roughly as much as in Stockholm.
Thursday's decline meant that the Stockholm stock exchange fell for the third day in a row. For October as a whole, the OMXS-index fell 4.3 percent and the year's gain is now 7.8 percent.