HELSINKI (Reuters) - Finland's outgoing Prime Minister Sanna Marin has filed for divorce jointly with her husband of three years Markus Raikkonen, they said on Instagram on Wednesday. Marin and Raikkonen, who until recently worked at a venture capital firm, share a 5-year-old daughter. They married in 2020 while Marin was in office dealing with the impact of the COVID-19 pandemic. Marin and her Social Democratic Party lost Finland's election for parliament last month, trailing the right-wing National Coalition Party as well as the nationalist Finns Party. Marin, 37, the world's youngest prime minister when she took office in 2019, is considered by fans around the globe as a millennial role model for progressive new leaders, even as voters at home opted for a new government.