Event study: American Express announced that it will not continue the co-brand deal with Costco On Feb 12th, 2014.

1.Graph the trend of prices and returns. By looking at the graph, does the event seem to affect performance?

2. What is the mean and standard deviation of the whole sample. Now find the mean & std. deviation of pre-window and compare it to the post window. Is there any noticeable difference in mean?

3.Find if there is a difference between pre and post event returns

a. Simple Mean Return Test: make a t-test to see if there is a difference of mean of normal return. Follow hypothesis testing steps.

b. Mean Excess Return Test: Find excess return. Is there a difference in mean in excess returns? Follow hypothesis testing steps.

(pre-event 11/3/2014 - 1/28/2015)

(event day 2/12/2015)

post event 2/13/2015- 3/31/2015

AXP Stock price Date Open Close Adj Close Volume SP 500 Close 11/3/2014 90.32 90.85 82.558189 3707900 2017.8101 11/4/2014 90.620003 91.38 83.039833 3163100 2012.1000 11/5/2014 91.760002 92.42 83.984917 3617600 2023.5699 11/6/2014 92.129997 91.58 83.221588 6005800 2031.2100 11/7/2014 91.709999 92.26 83.839516 3669200 2031.9200 11/10/2014 92.209999 92.40 83.966743 2938700 2038.2600 11/11/2014 92.279999 91.74 83.366974 2719800 2039.6801 11/12/2014 91.160004 91.55 83.194305 3825500 2038.2500 11/13/2014 91.699997 91.07 82.758118 3638000 2039.3300 11/14/2014 91.07 90.67 82.394623 2361600 2039.8199 11/17/2014 90.239998 90.13 81.903915 2620600 2041.3199 11/18/2014 90.209999 90.58 82.312859 2175500 2051.8000 11/19/2014 90.300003 90.50 82.240158 2661200 2048.7200 11/20/2014 89.830002 90.62 82.349182 2825700 2052.7500 11/21/2014 91.660004 90.39 82.140205 4039200 2063.5000 11/24/2014 90.800003 91.04 82.730881 3459500 2069.4099 11/25/2014 91.199997 91.40 83.057999 3313700 2067.0300 11/26/2014 91.709999 91.45 83.103416 2218200 2072.8301 11/28/2014 91.610001 92.42 83.984917 3070000 2067.5601 12/1/2014 92.07 92.14 83.730476 3343000 2053.4399 12/2/2014 92.599998 93.00 84.511978 3111900 2066.5500 12/3/2014 92.610001 91.25 82.921692 5911100 2074.3301 12/4/2014 91.849998 91.83 83.448761 3991000 2071.9199 12/5/2014 92.290001 92.65 84.193939 2872600 2075.3701 12/8/2014 92.68 93.56 85.020866 4467600 2060.3101 12/9/2014 92.190002 93.36 84.839119 4069100 2059.8201 12/10/2014 92.860001 92.75 84.284782 4658000 2026.1400 12/11/2014 93.110001 93.13 84.630127 4419100 2035.3300 12/12/2014 92.400002 91.00 82.694504 4480300 2002.3300 12/15/2014 91.440002 90.04 81.822121 4766700 1989.6300 12/16/2014 89.370003 88.24 80.186409 4948800 1972.7400 12/17/2014 88.559998 90.44 82.185638 5204400 2012.8900 12/18/2014 91.699997 93.17 84.666466 4554200 2061.2300 12/19/2014 92.959999 92.90 84.421104 7170300 2070.6499 12/22/2014 92.989998 93.62 85.075371 2910800 2078.5400 12/23/2014 93.699997 93.82 85.257126 2864800 2082.1699 12/24/2014 93.959999 94.08 85.493408 1321500 2081.8799 12/26/2014 94.199997 94.29 85.684227 1439900 2088.7700 12/29/2014 94 94.27 85.666061 1483000 2090.5701 12/30/2014 94.230003 94.27 85.666061 1425100 2080.3501 12/31/2014 94.650002 93.04 84.548325 2306200 2058.8999 1/2/2015 93.169998 93.02 84.530151 2437500 2058.2000 1/5/2015 92.459999 90.56 82.294662 3469600 2020.5800 1/6/2015 90.790001 88.63 80.54081 4800300 2002.6100 1/7/2015 91.010002 90.30 82.29985 5665200 2025.9000 1/8/2015 91.440002 91.58 83.466438 3774200 2062.1399 1/9/2015 91.580002 90.42 82.409225 3681700 2044.8101 1/12/2015 90.5 89.50 81.570717 3230700 2028.2600 1/13/2015 90.269997 89.23 81.324638 3537600 2023.0300 1/14/2015 87.440002 87.07 79.355988 6628400 2011.2700 1/15/2015 87.5 85.88 78.271408 5830900 1992.6700 1/16/2015 85.540001 86.04 78.417252 6768700 2019.4200 1/20/2015 86.459999 87.26 79.529167 6364100 2022.5500 1/21/2015 87.559998 87.67 79.902832 7185700 2032.1200 1/22/2015 84.5 84.37 76.895218 16390100 2063.1499 1/23/2015 84.43 84.13 76.676468 7366100 2051.8201 1/26/2015 83.779999 83.30 75.919991 6632800 2057.0901 1/27/2015 82.5 82.40 75.099731 6329500 2029.5500 1/28/2015 82.800003 81.73 74.48909 7942200 2002.1600 1/29/2015 82.07 82.00 74.735161 7545900 2021.2500 1/30/2015 82.120003 80.69 73.541237 7210500 1994.9900 2/2/2015 80.959999 82.13 74.853661 5459300 2020.8500 2/3/2015 82.580002 83.73 76.31192 5586200 2050.0300 2/4/2015 83.5 83.61 76.202538 6155700 2041.5100 2/5/2015 84.25 84.73 77.223335 3966600 2062.5200 2/6/2015 85.110001 85.01 77.478516 5139700 2055.4700 2/9/2015 84.529999 84.98 77.451164 3101300 2046.7400 2/10/2015 85.599998 85.84 78.23497 3589900 2068.5901 2/11/2015 85.870003 86.01 78.389908 4374800 2068.5300 2/12/2015 80.029999 80.48 73.349854 32653100 2088.4800 2/13/2015 79.440002 78.08 71.162491 34874400 2096.9900 2/17/2015 77.160004 79.08 72.073875 18578300 2100.3401 2/18/2015 78.720001 79.78 72.711853 13417000 2099.6799 2/19/2015 79.889999 78.40 71.454117 20858000 2097.4500 2/20/2015 78.220001 79.83 72.757439 11348700 2110.3000 2/23/2015 79.989998 80.30 73.185806 6868600 2109.6599 2/24/2015 80.300003 80.86 73.696167 10951000 2115.4800 2/25/2015 81.160004 82.17 74.890121 8184700 2113.8601 2/26/2015 83.010002 83.25 75.874435 8702800 2110.7400 2/27/2015 83.25 81.59 74.361504 8121200 2104.5000 3/2/2015 81.589996 82.03 74.762505 5503100 2117.3899 3/3/2015 80.989998 81.91 74.653152 6856100 2107.7800 3/4/2015 81.550003 80.63 73.486542 6141000 2098.5300 3/5/2015 80.660004 81.15 73.960487 5571800 2101.0400 3/6/2015 80.629997 80.31 73.194901 6530200 2071.2600 3/9/2015 80.150002 80.51 73.377182 5846100 2079.4299 3/10/2015 79.730003 79.11 72.101219 7525000 2044.1600 3/11/2015 79.400002 79.45 72.411079 4546200 2040.2400 3/12/2015 80.099998 81.56 74.334167 9386600 2065.9500 3/13/2015 81.5 80.60 73.459213 6919400 2053.3999 3/16/2015 80.879997 81.50 74.279503 5295100 2081.1899 3/17/2015 81.199997 81.06 73.878441 4258200 2074.2800 3/18/2015 80.580002 81.86 74.607574 6449400 2099.5000 3/19/2015 81.839996 81.54 74.315926 4677000 2089.2700 3/20/2015 81.790001 82.70 75.373146 9338100 2108.1001 3/23/2015 82.699997 82.20 74.917465 7291700 2104.4199 3/24/2015 82.040001 81.37 74.160988 5217800 2091.5000 3/25/2015 81.419998 80.11 73.012619 8908000 2061.0500 3/26/2015 79.669998 78.48 71.527046 16181300 2056.1499 3/27/2015 78.400002 77.97 71.06221 9022600 2061.0200 3/30/2015 78.349998 78.05 71.135139 7285200 2086.2400 3/31/2015 77.889999 78.12 71.43689 5918300 2067.8899 4/1/2015 78.050003 78.93 72.177589 6163500 2059.6899 4/2/2015 78.93 79.70 72.881737 5695200 2066.9600 4/6/2015 79.339996 79.63 72.817711 3831100 2080.6201 4/7/2015 78.589996 78.33 71.628929 5919200 2076.3301 4/8/2015 78.419998 78.69 71.95813 6405800 2081.8999 4/9/2015 78.629997 79.16 72.387924 4288100 2091.1799 4/10/2015 79.419998 79.59 72.78112 3442000 2102.0601 4/13/2015 79.730003 79.27 72.488503 4092000 2092.4299 4/14/2015 79.599998 79.49 72.689697 4213200 2095.8401 4/15/2015 79.43 79.75 72.927452 6042700 2106.6299 4/16/2015 79.43 80.91 73.988213 8084800 2104.9900 4/17/2015 78.400002 77.32 70.70533 22112500 2081.1799 4/20/2015 77.389999 77.23 70.623047 8432600 2100.3999 4/21/2015 77.379997 77.28 70.668755 5125000 2097.2900 4/22/2015 77.410004 78.44 71.72953 7318100 2107.9600 4/23/2015 78.059998 78.15 71.464325 4815400 2112.9299 4/24/2015 78.300003 77.99 71.318024 3400700 2117.6899 4/27/2015 77.830002 77.49 70.860786 6901700 2108.9199 4/28/2015 77.690002 77.49 70.860786 6493400 2114.7600 4/29/2015 77.129997 77.16 70.559013 4322600 2106.8501 4/30/2015 77.040001 77.45 70.824219 6754100 2085.5100 5/1/2015 77.849998 77.68 71.034546 3859200 2108.2900 5/4/2015 77.959999 78.28 71.583221 3896700 2114.4900 5/5/2015 77.980003 77.84 71.180847 5325800 2089.4600 5/6/2015 78.699997 77.85 71.189995 5896600 2080.1499 5/7/2015 77.839996 78.43 71.720375 7924600 2088.0000 5/8/2015 78.889999 78.98 72.22332 7198100 2116.1001 5/11/2015 79.050003 79.70 72.881737 5827400 2105.3301 5/12/2015 79.150002 79.08 72.314774 4575700 2099.1201 5/13/2015 79.5 79.86 73.028038 5494500 2098.4800 5/14/2015 80.339996 80.75 73.841896 4450800 2121.1001 5/15/2015 80.900002 80.22 73.357246 4479300 2122.7300 5/18/2015 80.279999 80.17 73.311508 4579900 2129.2000 5/19/2015 80.370003 81.36 74.399719 6063500 2127.8301 5/20/2015 81.410004 80.96 74.033943 3986700 2125.8501 5/21/2015 80.540001 80.76 73.851044 4249700 2130.8201 5/22/2015 80.839996 81.25 74.299118 3395800 2126.0601 5/26/2015 81.120003 80.19 73.329819 5282700 2104.2000 5/27/2015 80.449997 80.11 73.25666 5105100 2123.4800 5/28/2015 79.970001 80.09 73.238373 4443000 2120.7900 5/29/2015 80.040001 79.72 72.900024 7385100 2107.3899 6/1/2015 79.940002 79.47 72.67141 4716900 2111.7300 6/2/2015 79.260002 79.99 73.146919 4197300 2109.6001 6/3/2015 80.32 80.60 73.704742 4321400 2114.0701 6/4/2015 80.050003 79.36 72.570824 5438100 2095.8401 6/5/2015 79.739998 79.39 72.598259 4817000 2092.8301 6/8/2015 79.43 78.81 72.067863 5883600 2079.2800 6/9/2015 78.879997 79.17 72.397079 4506300 2080.1499 6/10/2015 79.199997 80.19 73.329819 5865400 2105.2000 6/11/2015 80.339996 80.30 73.43042 4013400 2108.8601 6/12/2015 80.43 79.53 72.726273 6253500 2094.1101 6/15/2015 79 79.25 72.47023 4929300 2084.4299 6/16/2015 79.040001 79.36 72.570824 6992700 2096.2900 6/17/2015 79.639999 80.32 73.448685 6945600 2100.4399 6/18/2015 80.239998 80.77 73.860191 4632300 2121.2400 6/19/2015 80.519997 80.19 73.329819 13054800 2109.9900 6/22/2015 80.68 81.25 74.299118 5548600 2122.8501 6/23/2015 81.440002 81.36 74.399719 5356300 2124.2000 6/24/2015 80.940002 80.74 73.832764 5637600 2108.5801 6/25/2015 80.989998 79.88 73.04631 6591100 2102.3101 6/26/2015 80.169998 79.88 73.04631 15746700 2101.4900