LetterOne and BASF Sign Letter of Intent to Merge Their Oil and Gas Businesses to Create Wintershall DEA PR Newswire LONDON, December 7, 2017 LONDON , December 7, 2017 /PRNewswire/ — BASF and L1 Energy, the energy investment arm of LetterOne, announce their intention to merge their oil and gas subsidiaries Wintershall DEA to be one of the largest independent European exploration and production companies Wintershall DEA to be governed jointly by L1 Energy and BASF , with joint headquarters in Hamburg and Kassel IPO envisaged in the medium term Closing could be expected in the second half of 2018 , subject to customary regulatory approvals, completion of due diligence process , and negotiation of definitive transaction agreements. There is n o assurance that the intended transaction will be consummated. […]