Example 4: A portfolio P and its benchmark portfolio B invest in equities and bonds only. Consider the following data for two consecutive months and show that neither arithmetic contributions nor arithmetic outperformances do add up to arithmetic outperformance: a) calculate the performance of P and B for month 1 , month 2 and the 2-month period. b) calculate the relative contributions of equities and bonds for each month (BF-model). c) show that the relative contributions do not add up to the 2-month arithmetic outperformance