Symmetry/anti-symmetry phase transitions in crude oil markets

Daily records of international crude oil prices are studied by means of a Zipf-type analysis. By using simple up-down information on price fluctuations, we have observed phase transitions between symmetric states, where occurrence of up and down fluctuations are almost equal, to anti-symmetric states, where there is a significant imbalance between up and down occurrences. Symmetric phase provides a time-scale domain for risk-neutral transactions. On the other hand, anti-symmetric phase can be exploited by speculators and consumers to accommodate contracts that take advantage of the spread between up and down occurrences. (C) 2003 Elsevier Science B.V. All rights reserved.