33 Cumulative Abnormal Returns National Airlines Group, Air France-KLM and Lufthansa announced purchases of planes on 18 July (18/7), 12 February (12/2) and 7 October (7/10), respectively. Given the following information, calculate the cumulative abnormal return (CAR) for these equities as a group. Graph the result and provide an explanation. All of the stocks have a beta of 1 and no other announcements are made.

National Airlines Group Air France-KLM Lufthansa Date Market Return Company Return Date Market Return Company Return Date Market Return Company Return 12/7 −0.3 −0.5 8/2 −0.9 −1.1 1/10 0.5 0.3 13/7 0.0 0.2 9/2 −1.0 −1.1 2/10 0.4 0.6 16/7 0.5 0.7 10/2 0.4 0.2 3/10 1.1 1.1 17/7 −0.5 −0.3 11/2 0.6 0.8 6/10 0.1 −0.3 18/7 −2.2 1.1 12/2 −0.3 −0.1 7/10 −2.2 −0.3 19/7 −0.9 −0.7 15/2 1.1 1.2 8/10 0.5 0.5 20/7 −1.0 −1.1 16/2 0.5 0.5 9/10 −0.3 −0.2 23/7 0.7 0.5 17/2 −0.3 −0.2 10/10 0.3 0.1 24/7 0.2 0.1 18/2 0.3 0.2 13/10 0.0 −0.1