In 1931 the company is founded in Thessaloniki.
Between the period 1950-1990, the commercial activity of the company is expanded to all of Greece, having another Steel Service Center based in Athens, and leading the local market in steel.
In 1991 the first cut-to-length line is installed. The company launches its processing activity.
In 1996 SIDMA acquires HELSIDER S.A., the oldest Greek Steel Service Center, based in Aspropyrgos.
In 1998 it merges with KAL S.A., a company trading and processing flat steel products.
In 1999 it joins forces with SIDENOR S.A.
In 2001 SIDMA obtains control of the newly formed company PANELCO S.A., which engages in the production of polyurethane steel sandwich panels.
In 2004 activity is expanded to Romania and Bulgaria.
In May 2005 the company is listed on the Athens Stock Exchange.
In 2007 the construction of 3 new Steel Service Centers, in Inofita, Bucharest and Sofia, is completed.
In 2009 the company`s headquarters move to its new facilities at Inofita.
In 2015 SIDMA acquires its subsidiary PANELCO.