1981 - Société d'Etudes et de Montages established Société d'Etudes et de Montages (SDEM) Erectors Nigeria Limited  as a Nigerian subsidiary of the French firm.
1994 – GEC Alstom acquired Société d'Etudes et de Montages in France 1994 and the firm became GEC ALSTOM SDEM. 
1996 - GEC ALSTOM divested from the company leading to the spin off of SDEM Erectors Nigeria Limited as an independent company now owned by the family of the French Managing Director at the time and the original Nigerian shareholder at inception of the Company in 1981. 
2004 – Global Energy Company Limited acquired majority (90%) shareholding in the Company with the French Family retaining 10% thereby making SDEM a subsidiary of Global energy Company.
2010 – Global Energy Company divests from the company and a new investor group backing the Management Team took over the company.