Deposit guarantee schemes have similarities with insurance schemes. A scheme with a low number of members and an uneven size distribution between the members is unfavorable because it provides low risk diversification.

The Commercial Banks' Guarantee Fund had 15 members at the end of 2002. The largest member – DnB – represented nearly half of the members' total assets. The Savings Banks' Guarantee Fund had 130 banks as members at the same time, but Gjensidige NOR Sparebank represented more than a third of the total assets of the members. When the banking units in former DnB and Gjensidige NOR Sparebank were to merge into the new DnB NOR Bank, a need arose for better risk diversification. Placing the new large banking unit in one of the two existing funds would be challenging. In 2005, the savings banks' and the commercial banks' guarantee funds were therefore merged into one joint fund: The Norwegian Banks' Guarantee Fund.