On Friday 9 March Cross Investments buys a bank bill with a par value of $1 million, maturing on Thursday 7 June. On Tuesday 8 May Cross Investments sells the bill to Zulu Capital. The following table shows bank bill yields pa for various terms on various dates.

Date Yield pa

30 days 60 days 90 days

9 Mar. 4.6% 4.7% 4.75%

8 May 4.4% 4.55% 4.65%

7 Jun. 4.3% 4.35% 4.35%

Assume that these bill transactions occur in Australia and are settled on the trade date. What effective annual rate of return has Cross Investments earned?