From 1996 until the spring of 2003, the official and so-called "commercial" exchange rate – both set administratively by the Central Bank – were highly overvalued. Many businesses and individuals were unable to buy dollars legally at these "low" rates, so a widespread black market developed to meet hard currency demand. The spread between the official exchange rate and the curb rate widened especially after the Russian financial crisis of August 1998: at the end of 1999 the curb rate stood at 550 som/US$ compared with the official rate of 140 som/US$, a gap by nearly a factor of 4 (up from a factor of "only" 2 in 1997 and the first half of 1998). By mid-2003, the government's stabilization and liberalization efforts had reduced the gap between the black market, official, and commercial rates to approximately 8% and it quickly disappeared as the som was made convertible after October 2003. Today, four foreign currencies—the U.S. dollar, the euro, the pound sterling, and the yen—are freely exchanged in commercial booths all around the cities, while other currencies, including the Russian ruble and the Kazakh tenge, are bought and sold by individual ("black market") money changers, who are allowed to operate openly without harassment. The foreign exchange regime since October 2003 is characterized as "controlled floating rate". Liberalization of the trade regime remains a prerequisite for Uzbekistan to proceed to an IMF-financed program. In 2012, "black market" rate is again significantly higher than official rate, 2850 som/US$ vs. 1865 som/US$ (as of mid-June 2011). This curb rate is often referred to as 'bazar rate', because money changers operate at or near 'bazars' - large farmer markets.