Your portfolio has a modified duration of 6 and a market value of $10 million. If interest rates suddenly drop by 50 basis points, what happens to your portfolio value?

你的投资组合修正久期（Modified Duration）是6，市值为1000万美元。如果市场利率突然下降50个基点，你的组合价值会发生什么变化？具体金额是多少？