Wikipedia
GKO and OFZ are abbreviations for ( : "Government Short-Term Commitments") and ( : "Federal Loan Obligations"), respectively. They are government bonds issued by the state of Russia.
GKOs are short-term zero-coupon Russian Government Treasury Bills. OFZs are coupon-bearing Federal Loan Bonds. Both are issued by the Russian Finance Ministry and trade on the Moscow Inter Bank Currency Exchange (MICEX), as well as on five other currency exchanges connected with the MICEX and located in large regional cities. GKOs were introduced in May 1993 as non-inflationary instruments for financing the budget deficit. OFZs were introduced in June 1995 to complement the GKO market as an instrument with medium and long-term standing.
The initials became synonymous with the 1998 Russian financial crisis when the state defaulted on its "GKO obligations" (bonds). The GKO crisis, the most significant financial crisis in post-Soviet Russia, caused turmoil amongst both foreign and domestic investors and creditors. The crisis led to the abrupt devaluation of the Russian ruble in several steps in August and September 1998. (In fact, the ruble first fell about four times, then after some oscillations stopped at that level.) The crisis severely undermined confidence in the ruble's stability, although such dramatic drops did not happen again until 2014.
After 1998 a new series of state bonds was issued. On 1 November 2006, the volume of the GKO-OFZ market reached 850.7 billion rubles at face value, having exceeded by 17.9% the volume reached at the beginning of the year. The market volume is growing as a result of the implementation of the RF Finance Ministry's policy of substituting the external debt for the internal debt and developing a liquid internal government-securities market, which must give market participants effective instruments to manage liquidity and form benchmarks for risk-free ruble interest-rates for all economic entities.