Final answer:
When investors sell a bond and buy a similar bond, it suggests that the expected returns on Bond A will start falling and the expected returns on Bond B will start rising.
Step-by-step explanation:
If we observe that many investors are selling Bond A and buying a similar Bond B, this suggests that the expected returns on Bond A will start falling.
When investors are selling a bond, it typically indicates a decrease in demand and can lead to a decline in price and an increase in yield, resulting in lower expected returns. Conversely, when investors are buying a bond, it suggests an increase in demand, leading to higher prices and lower yields, indicating that expected returns on Bond B will start rising.