Byr Sparisjóður was founded on the merger of four Icelandic savings banks:
  • Sparisjóður Vélstjóra
  • Sparisjóður Hafnarfjarðar
  • Sparisjóður Kópavogs
  • Sparisjóður Norðlendinga
 
Sparisjóður Vélstjóra and Sparisjóður Hafnarfjarðar merged on 1 December 2006 to form Byr Sparisjóður.
  • Sparisjóður Vélstjóra was founded in 1961.
  • Sparisjóður Hafnarfjarðar was founded in 1902 on the grounds of Sparisjóður Álftaneshrepps founded in 1875.
 
Sparisjóður Kópavogs merged with Byr Sparisjóður on 1 November 2007.
  • Sparisjóður Kópavogs was founded in 1954.
 
Sparisjóður Norðlendinga merged with Byr Sparisjóður on 1 April 2008.
  • Sparisjóður Norðlendinga was founded in 2007 when two savings banks merged, Sparisjóður Akureyrar og Arnarneshrepps and Sparisjóður Glæsibæjarhrepps.
  • Sparisjóður Akureyrar, founded in 1932, and Sparisjóður Arnarneshrepps, founded in 1884, merged in 1988 to form Sparisjóð Akureyrar og Arnarneshrepps.
  • Sparisjóður Glæsibæjarhrepps was founded in 1908.