You need to return data, not price data: IBM return is dependent variable and S&P500 return is independent variable. (Why?)

Date	Adj Close	Adj Close	Returns (%)
	IBM	S&P500 (^GSPC)	IBM	S&P500 (^GSPC)
1/3/11	145.61	1271.87
1/4/11	145.77	1270.2	0.110%	-0.131%
1/5/11	145.19	1276.56	-0.398%	0.501%
1/6/11	146.78	1273.85	1.095%	-0.212%
1/7/11	146.05	1271.5	-0.497%	-0.184%
1/10/11	145.77	1269.75	-0.192%	-0.138%
1/11/11	145.41	1274.48	-0.247%	0.373%
1/12/11	147.21	1285.96	1.238%	0.901%
1/13/11	146.93	1283.76	-0.190%	-0.171%
1/14/11	148.1	1293.24	0.796%	0.738%
1/18/11	148.74	1295.02	0.432%	0.138%
1/19/11	153.72	1281.92	3.348%	-1.012%
1/20/11	153.82	1280.26	0.065%	-0.129%
1/21/11	153.53	1283.35	-0.189%	0.241%
1/24/11	157.61	1290.84	2.657%	0.584%
1/25/11	159.39	1291.18	1.129%	0.026%
1/26/11	159	1296.63	-0.245%	0.422%
1/27/11	159.03	1299.54	0.019%	0.224%
1/28/11	157.19	1276.34	-1.157%	-1.785%
1/31/11	159.95	1286.12	1.756%	0.766%
2/1/11	161.49	1307.59	0.963%	1.669%
2/2/11	161.23	1304.03	-0.161%	-0.272%
2/3/11	161.46	1307.1	0.143%	0.235%
2/4/11	161.92	1310.87	0.285%	0.288%
2/7/11	162.73	1319.05	0.500%	0.624%
2/8/11	164.59	1324.57	1.143%	0.418%
2/9/11	163.21	1320.88	-0.838%	-0.279%
2/10/11	162.65	1321.87	-0.343%	0.075%
2/11/11	162.41	1329.15	-0.148%	0.551%
2/14/11	161.79	1332.32	-0.382%	0.238%
2/15/11	161.41	1328.01	-0.235%	-0.323%
2/16/11	161.97	1336.32	0.347%	0.626%
2/17/11	162.8	1340.43	0.512%	0.308%
2/18/11	163.39	1343.01	0.362%	0.192%
2/22/11	160.53	1315.44	-1.750%	-2.053%
2/23/11	158.78	1307.4	-1.090%	-0.611%
2/24/11	159.36	1306.1	0.365%	-0.099%
2/25/11	160.86	1319.88	0.941%	1.055%
2/28/11	160.46	1327.22	-0.249%	0.556%
3/1/11	158.57	1306.33	-1.178%	-1.574%
3/2/11	158.76	1308.44	0.120%	0.162%
3/3/11	162.05	1330.97	2.072%	1.722%
3/4/11	160.41	1321.15	-1.012%	-0.738%
3/7/11	158.53	1310.13	-1.172%	-0.834%
3/8/11	160.86	1321.82	1.470%	0.892%
3/9/11	164.41	1320.02	2.207%	-0.136%
3/10/11	160.6	1295.11	-2.317%	-1.887%
3/11/11	161.01	1304.28	0.255%	0.708%
3/14/11	159.97	1296.39	-0.646%	-0.605%
3/15/11	157.63	1281.87	-1.463%	-1.120%
3/16/11	151.66	1256.88	-3.787%	-1.949%
3/17/11	152.83	1273.72	0.771%	1.340%
3/18/11	154.52	1279.21	1.106%	0.431%
3/21/11	156.3	1298.38	1.152%	1.499%
3/22/11	156.61	1293.77	0.198%	-0.355%
3/23/11	158.13	1297.54	0.971%	0.291%
3/24/11	158.64	1309.66	0.323%	0.934%
3/25/11	160.76	1313.8	1.336%	0.316%
3/28/11	159.96	1310.19	-0.498%	-0.275%
3/29/11	161.45	1319.44	0.931%	0.706%
3/30/11	162.17	1328.26	0.446%	0.668%
3/31/11	161.64	1325.83	-0.327%	-0.183%
4/1/11	162.83	1332.41	0.736%	0.496%
4/4/11	162.81	1332.87	-0.012%	0.035%
4/5/11	162.55	1332.63	-0.160%	-0.018%
4/6/11	162.6	1335.54	0.031%	0.218%
4/7/11	162.94	1333.51	0.209%	-0.152%
4/8/11	162.61	1328.17	-0.203%	-0.400%
4/11/11	162.51	1324.46	-0.061%	-0.279%
4/12/11	161.82	1314.16	-0.425%	-0.778%
4/13/11	162.51	1314.41	0.426%	0.019%
4/14/11	163.52	1314.52	0.622%	0.008%
4/15/11	164.75	1319.68	0.752%	0.393%
4/18/11	164.48	1305.14	-0.164%	-1.102%
4/19/11	163.95	1312.62	-0.322%	0.573%
4/20/11	163.31	1330.36	-0.390%	1.351%
4/21/11	166.8	1337.38	2.137%	0.528%
4/25/11	166.2	1335.25	-0.360%	-0.159%
4/26/11	167.01	1347.24	0.487%	0.898%
4/27/11	168.88	1355.66	1.120%	0.625%
4/28/11	169.28	1360.48	0.237%	0.356%
4/29/11	169.08	1363.61	-0.118%	0.230%
5/2/11	170.64	1361.22	0.923%	-0.175%
5/3/11	171.35	1356.62	0.416%	-0.338%
5/4/11	169.12	1347.32	-1.301%	-0.686%
5/5/11	166.98	1335.1	-1.265%	-0.907%
5/6/11	168.16	1340.2	0.707%	0.382%
5/9/11	168.37	1346.29	0.125%	0.454%
5/10/11	169.64	1357.16	0.754%	0.807%
5/11/11	168.77	1342.08	-0.513%	-1.111%
5/12/11	171.49	1348.65	1.612%	0.490%
5/13/11	169.18	1337.77	-1.347%	-0.807%
5/16/11	168.13	1329.47	-0.621%	-0.620%
5/17/11	169.76	1328.98	0.969%	-0.037%
5/18/11	169.7	1340.68	-0.035%	0.880%
5/19/11	169.85	1343.6	0.088%	0.218%
5/20/11	169.42	1333.27	-0.253%	-0.769%
5/23/11	167.53	1317.37	-1.116%	-1.193%
5/24/11	167.26	1316.28	-0.161%	-0.083%
5/25/11	167.02	1320.47	-0.143%	0.318%
5/26/11	166.46	1325.69	-0.335%	0.395%
5/27/11	166.77	1331.1	0.186%	0.408%
5/31/11	168.2	1345.2	0.857%	1.059%
6/1/11	165.84	1314.55	-1.403%	-2.278%
6/2/11	165.37	1312.94	-0.283%	-0.122%
6/3/11	164.33	1300.16	-0.629%	-0.973%
6/6/11	164.04	1286.17	-0.176%	-1.076%
6/7/11	162.98	1284.94	-0.646%	-0.096%
6/8/11	163.63	1279.56	0.399%	-0.419%
6/9/11	164.13	1289	0.306%	0.738%
6/10/11	162.47	1270.98	-1.011%	-1.398%
6/13/11	162.46	1271.83	-0.006%	0.067%
6/14/11	163.41	1287.87	0.585%	1.261%
6/15/11	161.63	1265.42	-1.089%	-1.743%
6/16/11	161.96	1267.64	0.204%	0.175%
6/17/11	163.73	1271.5	1.093%	0.305%
6/20/11	164.3	1278.36	0.348%	0.540%
6/21/11	165.5	1295.52	0.730%	1.342%
6/22/11	164.96	1287.14	-0.326%	-0.647%
6/23/11	165.4	1283.5	0.267%	-0.283%
6/24/11	164.35	1268.45	-0.635%	-1.173%
6/27/11	166.89	1280.1	1.545%	0.918%
6/28/11	169.27	1296.67	1.426%	1.294%
6/29/11	169.8	1307.41	0.313%	0.828%
6/30/11	170.81	1320.64	0.595%	1.012%
7/1/11	173.78	1339.67	1.739%	1.441%
7/5/11	174.67	1337.88	0.512%	-0.134%
7/6/11	176.94	1339.22	1.300%	0.100%
7/7/11	175.71	1353.22	-0.695%	1.045%
7/8/11	175.72	1343.8	0.006%	-0.696%
7/11/11	174.23	1319.49	-0.848%	-1.809%
7/12/11	173.3	1313.64	-0.534%	-0.443%
7/13/11	173.56	1317.72	0.150%	0.311%
7/14/11	173.47	1308.87	-0.052%	-0.672%
7/15/11	174.78	1316.14	0.755%	0.555%
7/18/11	174.52	1305.44	-0.149%	-0.813%
7/19/11	184.41	1326.73	5.667%	1.631%
7/20/11	182.85	1325.84	-0.846%	-0.067%
7/21/11	184.1	1343.8	0.684%	1.355%
7/22/11	184.38	1345.02	0.152%	0.091%
7/25/11	182.9	1337.43	-0.803%	-0.564%
7/26/11	182.14	1331.94	-0.416%	-0.410%
7/27/11	180.56	1304.89	-0.867%	-2.031%
7/28/11	181.01	1300.67	0.249%	-0.323%
7/29/11	181.06	1292.28	0.028%	-0.645%