Delta, United, and American Airlines announced purchases of planes on July 18 (7/18), February 12 (2/12), and October 7 (10/7), respectively, Delta United American Date Market Company Date Market Company Date Market Company Return Return Return Return Return Return 7/12 -0.43 -0.65 2/8 -0.92 -1.24 10/1 0.63 0.39 7/13 0.00 0.33 2/9 -1.02 -1.24 10/2 0.53 0.71 7/16 1.28 1.59 2/10 0.53 0.22 10/3 1.23 1.23 7/17 -1.28 -1.08 2/11 0.73 3.53 10/6 0.23 -2.77 7/18 -2.22 1.12 2/12 -0.43 -0.18 10/7 -2.33 -0.44 7/19 -0.86 -0.69 2/15 1.23 2.91 10/8 0.63 0.63 7/20 -0.92 -1.16 2/16 0.63 0.63 10 -0.43 -0.19 7/23 0.74 0.52 2/17 -0.43 -0.32 10/10 0.43 -0.24 7/24 0.23 0.07 2/18 0.43 0.29 10/13 0.00 -0.23 Given the above information, calculate the cumulative abnormal return (CAR) for these stocks as a group. All of the stocks have a beta of 1 and no other announcements are made