99. Volumes in "Over the Counter" derivatives generally slowed in the first half of 1999 as all major financial markets stabilised following significant event risk over both the preceding half year (1998) and also the previous Autumn (1997). Risk-taking positions by market professionals reduced over that period, as well as the use of swap spreads as a "proxy" for credit spread risk mitigation (ie the use of swaps to protect against movements in credit spreads). The swap market in the second half of 1998 had seen unusual and significant use, notably by investment banks and dealers to mitigate their exposures to rising credit spreads. Swap spreads in the second half of 1998 in the major markets had widened dramatically to historic highs, particularly in the 10-year plus sector. During the first half of 1999, swap spreads gradually, but consistently, declined. The mechanics of the swap market are described in Annex 4.