Problem $14-1$ Cumulative Abnormal Returns

Delta, United, and American Airlines announced purchases of planes on July $18(7/18),$ February $12(2/12),$ and October $7(10/7),$ respectively.

$\backslash$table$[[$Delta$,$United,American$],[,$Market,Company,,Market,Company,,Market,Company$],[$Date$,$Return,Return,Date,Return,Return,Date,Return,Return$],[7/12,-\mathrm{.}43,-\mathrm{.}65,2/8,-\mathrm{.}92,-1\mathrm{.}24,10/1,\mathrm{.}63,\mathrm{.}39],[7/13,\mathrm{.}00,\mathrm{.}33,2/9,-1\mathrm{.}02,-1\mathrm{.}24,10/2,\mathrm{.}53,\mathrm{.}71],[7/16,1\mathrm{.}28,1\mathrm{.}59,2/10,\mathrm{.}53,\mathrm{.}22,10/3,1\mathrm{.}23,1\mathrm{.}23],[7/17,-1\mathrm{.}28,-1\mathrm{.}08,2/11,\mathrm{.}73,3\mathrm{.}53,10/6,\mathrm{.}23,-2\mathrm{.}77],[7/18,-2\mathrm{.}22,1\mathrm{.}12,2/12,-\mathrm{.}43,-\mathrm{.}18,10/7,-2\mathrm{.}33,-\mathrm{.}44],[7/19,-\mathrm{.}86,-\mathrm{.}69,2/15,1\mathrm{.}23,2\mathrm{.}91,10/8,\mathrm{.}63,\mathrm{.}63],[7/20,-\mathrm{.}92,-1\mathrm{.}16,2/16,\mathrm{.}63,\mathrm{.}63,10/9,-\mathrm{.}43,-\mathrm{.}19],[7/23,\mathrm{.}74,\mathrm{.}52,2/17,-\mathrm{.}43,-\mathrm{.}32,10/10,\mathrm{.}43,-\mathrm{.}24],[7/24,\mathrm{.}23,\mathrm{.}07,2/18,\mathrm{.}43,\mathrm{.}29,10/13,\mathrm{.}00,-\mathrm{.}23]]$

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. $($A negative answer should be indicated by a minus sign. Leave no cells blank be certain to enter $"0"$ wherever required. Do not round intermediate calculations and round your answers to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)\backslash$table$[[\backslash$table$[[$Days from$],[$announcement$]],$Abnormal returns $($R$\_($i$)-$R$\_($M$)),\backslash$table$[[$Average abnormal$],[$return$]],\backslash$table$[[$Cumulative$],[$abnormal return$]]],[$Delta$,$United,American,Sum$],[-4],[-3],[-2],[-1],[0],[1],[2],[3],[4,,,,,,]]$