Activity in global OTC derivatives markets fell in the first half of 2015. The notional amount of outstanding contracts declined from $629 trillion at end-December 2014 to $553 trillion at end-June 2015. Even after adjustment for the effect of exchange rate movements on positions denominated in currencies other than the US dollar, notional amounts were still down by about 10%. Trade compression to eliminate redundant contracts was the major driver of the decline. [...]