Photo, via Wikimedia Commons ↗
About
Sebastian Siemiatkowski's idea finished near the bottom of his business school's entrepreneurship competition in 2005. He built it anyway. Twenty years later Klarna serves more than 120 million consumers and a million merchants across 26 countries on $3.5 billion of annual revenue and $127.9 billion of volume, holds a full Swedish banking licence, and listed on the New York Stock Exchange in September 2025 at $40 a share — the largest NYSE listing of the year. He co-founded the company at 23 with two Stockholm School of Economics classmates, having worked out the problem while selling invoice factoring to small businesses; before that he was a telemarketer at 17 and, at 15, flipped burgers alongside his future co-founder Niklas Adalberth. The son of Polish immigrants to Uppsala, he has since run one of the most aggressive AI transformations of any public company and co-founded the listed investment vehicle Flat Capital with his wife Nina.
Beyond investing
- Education
- Read economics at the Stockholm School of Economics, starting Klarna at 23 while on sabbatical from his studies.
- Family
- Born in Uppsala in 1981 to Polish parents who emigrated to Sweden in 1980; he worked at Burger King at 15 and as a telemarketer at 17.
- More
- The three founders pitched the pay-after-delivery idea at their business school's 2005 entrepreneurship competition and placed near the bottom.
From Sebastian's own website — common ground for a warm intro.
Co-founder & CEO at Klarna
Intro paths
In turn, Sebastian can intro founders to Klarna's investors below.
Klarna's investors · 32
Co-founders at Klarna
Frequently asked questions
- Who is Sebastian Siemiatkowski?
- Sebastian Siemiatkowski's idea finished near the bottom of his business school's entrepreneurship competition in 2005. He built it anyway. Twenty years later Klarna serves more than 120 million consumers and a million merchants across 26 countries on $3.5 billion of annual revenue and $127.9 billion of volume, holds a full Swedish banking licence, and listed on the New York Stock Exchange in September 2025 at $40 a share — the largest NYSE listing of the year. He co-founded the company at 23 with two Stockholm School of Economics classmates, having worked out the problem while selling invoice factoring to small businesses; before that he was a telemarketer at 17 and, at 15, flipped burgers alongside his future co-founder Niklas Adalberth. The son of Polish immigrants to Uppsala, he has since run one of the most aggressive AI transformations of any public company and co-founded the listed investment vehicle Flat Capital with his wife Nina.
- Where does Sebastian Siemiatkowski work?
- Sebastian Siemiatkowski is Co-founder & CEO at Klarna.
- What companies did Sebastian Siemiatkowski found?
- Sebastian Siemiatkowski founded Klarna.
Paths to reach Sebastian
People who overlapped with Sebastian at the same organization — a shared school or employer with one of them is a warm way in.