LetterOne Holdings S.A. (LetterOne) is an international investment business based in Luxembourg. With long-term investments in the telecoms, technology, healthcare, and energy sectors, the firm has four main units: L1 Health, L1 Technology, L1 Retail, and L1 Energy, all of which are supported by L1 Treasury Services, which manages the group's liquidity. LetterOne was set up LetterOne in 2013 as part of a broader new investment vehicle using the proceeds from the sale of TNK-BP. LetterOne had $26.8 billion in equity at the end of 2021. Co-founders Mikhail Fridman and Petr Aven "officially" stepped down from the company in early March 2022, after the EU imposed sanctions on them in the wake of the Russian invasion of Ukraine.
Two sanctioned Russian oligarchs have become co-owners of Britain's biggest oil producer after it completed a deal to buy the German company. LetterOne, an investment company partly owned by oligarchs Mykhailo Fridman and Petr Aven, now owns almost 15% of Harbor Energy. Harbor Energy is the largest producer of oil and gas in UK waters. It bought most of the oil and gas assets of the German firm Wintershall DEA from the chemical giant BASF. LetterOne co-owned Wintershall and the shares were exchanged for Harbor Energy shares.