You have a portfolio of three investments, A, B, and C with the following characteristics:

Last quarter the portfolios standard deviation was 7.2%, but this quarter the standard deviation increased (versus last quarter) to 2.1%. Thats quite a decrease in just one quarter. What are the potential causes of this?

Return Standard Deviation Investment A Investment B Investment C 10% 6% 3% 8% 5% 1% Correlation Matrix Investment A Investment B Investment C 1 0.5 0.4 0.6 1 1 1