Assuming that the effective rate of return of investors investing in sterling is F, and the exchange rate between sterling and the US dollar is 1 sterling =E at first, then according to the meaning of the question, it is: (F-E)/ 10000 =-9%, which means that F/E=9 1%. The 6-month return of a dollar principal is: A/E? (1+5%), the 6-month GBP income of USD A principal is converted into USD:

A/E？ ( 1+5%)? F=A？ ( 1+5%)? F/E=A？ ( 1+5%)? 9 1%=95.6%A

Therefore, the effective rate of return of investors who invest in sterling is: (95.6%A- 100%A)/A=-4.4%.