2 pts SoftBank Group made an announcement at time to that it was acquiring a proportion of Sony Corporation. The returns over the announcement period were: Day (t) Market returns Sony Corporation stock returns -3 +0.1 -0.2 -2 +0.2 -1 +0.1 -0.3 o -0.8 +0.5 +0.2 +1 o -0.5 +2 -0.2 +0.3 +3 -0.4 +0.4 What would be the cumulative abnormal return for this seven day period? -40% +50% -10% +20% -50%