I have noticed how for some reason assets classes across unrelated markets seem to be moving in tandem. During the past few weeks on several occasions prices for currencies, indices, metals, energy, grains and interest rates have moved together. Fridays selloff in everything listed above is another clear example. Does anybody have any idea if this is related to computer based models using the exact same trading code ? Can a few hedgies command so much control over so many different markets at the same time?