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$],[\frac{7}{12},-\mathrm{.}47,-\mathrm{.}73,2/8,-\mathrm{.}96,-1\mathrm{.}32,10/1,67,35],[\frac{7}{13},\mathrm{.}00,37,\frac{2}{9},-1\mathrm{.}06,-1\mathrm{.}32,\frac{10}{2},\mathrm{.}57,\mathrm{.}79],[\frac{7}{16},1\mathrm{.}97,2\mathrm{.}21,\frac{2}{10},\mathrm{.}57,\mathrm{.}33,\frac{10}{3},1\mathrm{.}27,1\mathrm{.}27],[\frac{7}{17},-1\mathrm{.}97,-1\mathrm{.}69,\frac{2}{11},\mathrm{.}77,4\mathrm{.}33,\frac{10}{6},\mathrm{.}27,-3\mathrm{.}57],[\frac{7}{18},-2\mathrm{.}26,1\mathrm{.}16,\frac{2}{12},-\mathrm{.}47,-\mathrm{.}14,\frac{10}{7},-2\mathrm{.}37,-\mathrm{.}40],[\frac{7}{19},-\mathrm{.}90,-\mathrm{.}65,\frac{2}{15},1\mathrm{.}27,3\mathrm{.}53,\frac{10}{8},\mathrm{.}67,\mathrm{.}67],[\frac{7}{20},-\mathrm{.}96,-1\mathrm{.}09,\frac{2}{16},67,67,\frac{10}{9},-\mathrm{.}47,-\mathrm{.}34],[\frac{7}{23},\mathrm{.}78,48,\frac{2}{17},-\mathrm{.}47,-\mathrm{.}28,\frac{10}{10},47,-\mathrm{.}33],[\frac{7}{24},\mathrm{.}27,\mathrm{.}03,\frac{2}{18},\mathrm{.}47,25,\frac{10}{13},\mathrm{.}00,-\mathrm{.}27]]$

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$.,32\mathrm{.}16.)$

Answer is not complete.

$\backslash$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$],[-4,-0\mathrm{.}26vv,-0\mathrm{.}36vv,-0\mathrm{.}32vv,-0\mathrm{.}94vv,-0\mathrm{.}31vv,-0\mathrm{.}31$