LetterOne was set up in 2013 as part of a broader new investment vehicle using the proceeds from the sale of
TNK-BP. On 2 March 2015,
Lord Browne was named executive chairman of
L1 Energy, renouncing his other roles to focus on the newly formed oil and gas company. On 4 March 2015, the
Secretary of State for Energy and Climate Change,
Ed Davey, gave company co-founder
Mikhail Fridman a one-week deadline to convince the UK government not to force him to sell the newly acquired
North Sea oil and gas assets. A senior western oil executive said the UK was entering "uncharted territory" by intervening publicly in a corporate transaction over fears of the effect of future sanctions against Russia. In October 2015 LetterOne sold its North Sea oil fields to Ineos, the chemical company, for an undisclosed sum. The
Financial Times has since reported that LetterOne has been told in a letter from a senior government official that the previous Energy Secretary's decision to require the sale of the North Sea fields "is not a judgement on the suitability of LetterOne’s owners to control these or any other assets in the UK". On 14 October 2015 LetterOne Group announced that it had agreed a deal to acquire German utility Eon’s interests in three producing Norwegian fields, located in the
North Sea. Norway’s oil minister said that approval would be handled ‘in the usual way’. LetterOne's first annual LetterOne Rising Stars Jazz Award was awarded in 2017. The firm's investment unit L1 Retail launched in December 2016. Working with a $3 billion fund focused on Europe sans Russia, the unit initially acquired
Holland & Barrett, a healthcare retailer in the United Kingdom, in 2017 for £1.77 billion. LetterOne gained total control of Spanish retailer
DIA in May 2019 when it acquired 70% of its shares, after having first bought 29% in 2017. Also in 2019, the firm's unit L1 Health acquired the pet heath platform Destination Pet and was a founding investor in K2 HealthVentures. After receiving regulatory approval in nine countries, LetterOne merged its oil and gas businesses into
Wintershall Dea, a new European exploration and production company, in May 2019. LetterOne held 33% of the shares, with the rest owned by
BASF. LetterOne invested £1 billion in the infrastructure company Upp in 2021, and also in 2021, L1 Health acquired Remedica, a pharmaceutical company in Cyprus. LetterOne had $26.8 billion in equity at the end of 2021, up from $22.3 billion the year prior. in February 2022, LetterOne invested in H2scan Corporation, a California-based company that builds gas monitoring systems. ==Units and investment areas==