  The gauge theory of arbitrage was introduced by Ilinski in
[arXiv:hep-th/9710148] and applied to fast money flows in
[arXiv:cond-mat/9902044]. The theory of fast money flow dynamics attempts to
model the evolution of currency exchange rates and stock prices on short, e.g.\
intra-day, time scales. It has been used to explain some of the heuristic
trading rules, known as technical analysis, that are used by professional
traders in the equity and foreign exchange markets. A critique of some of the
underlying assumptions of the gauge theory of arbitrage was presented by
Sornette in [arXiv:cond-mat/9804045]. In this paper, we present a critique of
the theory of fast money flow dynamics, which was not examined by Sornette. We
demonstrate that the choice of the input parameters used in
[arXiv:cond-mat/9902044] results in sinusoidal oscillations of the exchange
rate, in conflict with the results presented in [arXiv:cond-mat/9902044]. We
also find that the dynamics predicted by the theory are generally unstable in
most realistic situations, with the exchange rate tending to zero or infinity
exponentially.
