The aims of the present study are to examine the distribution of monthlyreturn from convertible preferred stocks(CPS)in Taiwan stock market,to searchthe anomaly of seasonality,especially the January effect,and to analyze therelationship between macroeconomic factors and the CPS monthly return.Here,the exchange rate,interest rate,and money supply are considered as themacroeconomic factors in the investigation.The results reveal that secondarymarket of the Taiwan CPS did not reach weak form efficiency because theobvious effect of anomaly on the CPS monthly return occurs in January,February,March,May,June,August and December.