Based on risk aversion, this paper presents the online trading strategy of bounded daily exchange rate that fluctuates between different ranges. Under  this strategy, we analyze the upper and lower bounds of  the competitive ratio with linear growth daily exchange rate and total trading periods and compare the performance of competitive ratio between linear growth model and loggrowth model. Examples show that this risk aversion policy is more suitable for exchange rate which fluctuates in the smooth.

online trading    conservative strategy    performance of competitive ratio    smooth fluctuation