Flat Capital

Flat Capital (Flat Capital AB, publ) is a publicly listed family office founded in 2013 by Nina and Sebastian Siemiatkowski (co-founder and CEO of Klarna) and listed on the Stockholm Stock Exchange in 2021 under the ticker FLAT B. Based in Stockholm, Sweden, it operates with a broad investment mandate covering public and private companies, minority and majority stakes, and Swedish and global targets. The firm primarily targets growth-stage companies and acts as a long-term, largely passive co-investor with no fixed investment cycles or fund fees. Its 30+ company portfolio spans AI, fintech, life sciences, defense, logistics, and space, with notable holdings including Klarna, SpaceX, OpenAI, Defensor, Pixelgen Technologies, and Oden Technologies. As of 2026, Flat reports a net asset value of approximately 5,545 MSEK and total invested capital of approximately 9,975 MSEK. The firm does not publish an open application process; deal flow is sourced through its founders' global network of entrepreneurs, investors, and executives.