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.