Complex sentence: In 1981 he was elected president of the board of directors of Zoilo Ruiz-Mateos SA and director of the Bank Atlantic, both belonging to the business group Rumasa, positions he held until 1983.
Split into simpler sentences: In 1981 he was elected president of the board of directors of Zoilo Ruiz-Mateos SA and he also became the director of the Bank Atlantic. Both organizations belonged to the business group Rumasa, These were positions he held until 1983.