Quoting Pascal Lottaz & Ingemar Ottosson’s Sweden, Japan, and the Long Second World War: 1931–1945, page 4:

Although Japan was Sweden’s largest trading partner in Asia, it was not a vital market, not in comparison to its bellicose neighbors for which, in the same year, 21 percent of imports came from Germany, 16 from the United States, and 12 from Britain respectively.

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Page 6:

Once the European war started, Sweden’s two biggest problems were its dominant position as one of the continent’s largest exporters of iron ore and its geographical position between the belligerents. Iron ore was a crucial primary material for the production of steel, abundant in Sweden’s north, but exceedingly rare in central Europe. That created a sensitive vulnerability for Germany who, by 1939, imported roughly 40 percent of its iron ore from Sweden. Had these shipments ceased, the [Fascist] armament industry would have seriously suffered. In fact, the raw material was so essential to [Fascist] industry that Swedish diplomat Gunnar Hägglöf was convinced that had the iron ore mines been located in the south, Germany would most likely have occupied Sweden for the sake of uninterrupted access.

Their isolated location in the high north and the implicit threat that should an attack happen, Sweden would destroy these facilities before an aggressor could seize them, provided a strong discouragement to any [Fascist] military intervention, and gave Sweden a bargaining chip in economic negotiations with both sides. Together with Sweden’s exports of ball bearings, the iron ore supply was the country’s most vital “contribution” to [the Reich’s] war economy. Naturally, Britain, once at war with Germany, demanded that Sweden cease all exports, even threatening to attack Swedish mines should shipments continue. Four years later, it was the U.S. chief negotiator who threatened bombing factories and distribution centers in Gothenburg should Swedish exports of iron ore and ball bearings to Germany not end.

Germany, on the other side, threatened to stop crucial deliveries of coal, coke, and steel if Sweden did not meet the demanded quotas of iron ore exports. Stockholm solved the problem by negotiating War Trade Agreements with Great Britain and Germany (in late 1939 and early 1940), reaching compromises with both of them. All political provisions were, however, highly volatile, depending heavily on the developments of the war. After Germany attacked and occupied Denmark and Norway on April 9, 1940, Swedish trade with Allied nations was cut off to a large extent, which led to even closer integration of Swedish commerce with the [Fascist] “Grossraumwirtschaft” (the [Axis] vision for a continental economic zone).