On July 1, 1997, Bulgaria implemented a currency board system, known as the "currency board," in response to a severe economic crisis marked by hyperinflation and widespread social unrest. The crisis was precipitated under the government of the Bulgarian Socialist Party led by Zhan Videnov, which prioritized preserving jobs and maintaining state-owned enterprises, neglecting market reforms.

During this period, the government significantly increased control over prices, leading to distortions in supply and demand dynamics. At the same time, efforts to accelerate foreign debt repayment and control the exchange rate depleted foreign exchange reserves, causing a sharp depreciation of the Bulgarian lev and raising concerns about defaulting on debt payments.

State-owned enterprises, despite being financially unsustainable, received subsidies and loans from state banks, exacerbating the country's financial instability. The lack of oversight over commercial banks allowed them to issue unsecured loans, contributing to a banking crisis and a loss of confidence in the financial system by early 1996.

The economic turmoil worsened in 1997, with inflation skyrocketing to alarming levels: by the first four months, it reached 438%. Public confidence in the Bulgarian lev plummeted, leading to long queues at banks and currency exchange offices.

In addition to financial woes, Bulgaria faced a grain crisis in 1996 due to mismanagement of grain exports, causing shortages and further straining the economy. The government's reluctance to adopt market-based solutions exacerbated the crisis, underscoring its mismanagement of the situation.

By late 1996, the economic collapse forced the government to resign, marking a critical juncture known as the "Winter of Videnov." The International Monetary Fund stepped in to assist Bulgaria on the condition that it adopt a currency board regime, which was officially implemented on July 1, 1997, under the Law on the Bulgarian National Bank.

The introduction of the currency board regime stabilized Bulgaria's economy in subsequent years, attracting foreign investments and accelerating economic growth. Inflation dropped significantly from 210% annually to 1% by the end of 1998, while foreign exchange reserves surged from under 800 million US dollars to over 3 billion USD.

Initially pegged to the German mark at a rate of 1,000 leva per mark, Bulgaria later adjusted its currency to align with the euro, setting it at 1.95583 leva per euro following the euro's introduction and the lev's denomination on July 5, 1999.