We analyze data from 2005 through 2009 that uniquely identify categories of traders to assess how speculators such as hedge funds and swap dealers relate to volatility and price changes. Examining various subperiods where price trends are strong, we find little evidence that speculators...

We present CoMargin, a new methodology to estimate collateral requirements for central counterparties (CCPs) in derivatives markets. CoMargin depends on both the tail risk of a given market participant and its interdependence with other participants. Our approach internalizes market...