“I find that the remuneration in question can not be considered as an inappropriate payment for Carl Bildt’s work. There is therefore no question of wrongdoing,” prosecutor Christer van der Kwast said in a statement.
The stock options were in a Swedish investment group which, in turn, is based on shares in Russian state-controlled Gazprom.
Van der Kwast began a preliminary inquiry into Bildt’s sale of the options in case Bildt had benefited from an “inappropriate privilege”.
He described the possible offences as “bribery and corruption”.
Bildt sold his stock options in December sparking controversy in the Swedish media and the left-wing opposition over a possible conflict of interest.
Ninety percent of the assets held by the investment group, Vostok Nafta, are shares in Gazprom which in turn is majority owned by the Russian government.
Gazprom currently has plans to build a gas pipeline from Russia to Germany via Sweden’s economic maritime zone, and the Swedish government is expected to take a stand on the project at some point.
Bildt left his position on the board of Vostok Nafta after being named foreign minister in early October.
The sale of his stock options raised 4.8 million kronor, according to the media.