Founder Profile
Sebastian Siemiatkowski
Last reviewed: October 2026 · By Swet Parvadiya
Who is Sebastian Siemiatkowski?
Sebastian Siemiatkowski is a founder of Klarna Group plc, which was founded in 2005 with Niklas Adalberth and Victor Jacobsson.
- Company founded
- Klarna Group plc
- Founded
- 2005
- Co-founders
- Niklas Adalberth and Victor Jacobsson
Background
Siemiatkowski co-founded Klarna in 2005 while studying at the Stockholm School of Economics and has been CEO since.
Founding Story
Sebastian Siemiatkowski, born in 1981 in Sweden to Polish immigrant parents, co-founded Klarna (originally Kreditor) with Niklas Adalberth and Victor Jacobsson in 2005. The pitch, receive goods first and pay later while Klarna takes the risk, reportedly did poorly at the school's business competition, but the founders went ahead with backing from angel investor Jane Walerud. As CEO he expanded Klarna across Europe and into the US, led it through the 2022 valuation reset, became one of the best-known corporate advocates of AI, and took the company public on the NYSE in September 2025.