stocks_18 <-
structure(list(date = structure(c(16740, 16770, 16801, 16832, 
16861, 16892, 16922, 16953, 16983, 17014, 17045, 17075, 17106, 
17136, 17167, 17198, 17226, 17257, 17287, 17318, 17348, 17379, 
17410, 17440, 17471, 17501, 17532, 17563, 17591, 17622, 17652, 
17683, 17713, 17744, 17775, 17805), class = "Date"), cat = c(-0.064556218520330333, 
-0.084167130209569174, 0.11569270640625115, 0.13057610254030716, 
0.015416997072568949, -0.057938775822212088, 0.045510821270779392, 
0.091676784771333772, -0.00024830244572909507, 0.083221269997722502, 
-0.059817272168055255, 0.15508663770407105, -0.029510297125528172, 
0.031485867515504008, 0.018837974426537861, -0.040347736261406905, 
0.10241492234489387, 0.039563176303886068, 0.019254458344578042, 
0.060394685840246869, 0.038508753879973358, 0.061451997160430011, 
0.0889263868942307, 0.04559573674638083, 0.11640105032350438, 
0.032999086313957031, -0.045658473478567017, -0.04688610197202811, 
-0.020491290308127075, 0.057597985853271347, -0.10690543279658203, 
0.059924923989997422, -0.02850248386531434, 0.098235496223661636, 
-0.20440682827211343, 0.014253577037782914), goog = c(0.021923013097431093, 
-0.020991451738143988, -0.060811617565462758, 0.067615389953268504, 
-0.069722801749548868, 0.06162964514754992, -0.059288855433285527, 
0.11080769348271159, -0.0022632839264198033, 0.013349833987612336, 
0.0093272783712644233, -0.033777756064841347, 0.018178499023701906, 
0.0323520649549578, 0.03315810279933009, 0.0077136767414135903, 
0.092097044438249343, 0.065013865479375502, -0.058174248981835527, 
0.02395653327075227, 0.0094895400322407286, 0.021057527857113133, 
0.059982724504739564, 0.0046918849638237859, 0.02446622968307359, 
0.11806184457809231, -0.0557378705647592, -0.066025130412410898, 
-0.014014500483077431, 0.066507398650756652, 0.028258356558662809, 
0.091076936148571208, 0.00076395428450830663, -0.020292377377297766, 
-0.097782058900248658, -0.047373170735195591), xom = c(-0.037110886675639616, 
-0.0012828189094055895, 0.029544012471087237, 0.052385137804470808, 
0.057542761793703184, 0.0070135848179126645, 0.061871924845433426, 
-0.051098975281977023, -0.020348431466315268, 0.010147767634895187, 
-0.045371091973699283, 0.047767653458873433, 0.043061011888122877, 
-0.07057389163900922, -0.030635315699806431, 0.017706898401684434, 
-0.0043898210524688482, -0.014084496324083292, 0.012327371210007666, 
-0.0085469647273413388, -0.046351961229173837, 0.08443114201221559, 
0.016711295920763942, -0.00071993033888973911, 0.013495957188191406, 
0.043758979622632581, -0.13241703591044487, -0.004846130875866674, 
0.042085334989258982, 0.044887483787843831, 0.02866267999298213, 
-0.014746772341339622, -0.016439719883543188, 0.071434864546648325, 
-0.062808724092910911, -0.034010996221100438)), row.names = c(NA, 
-36L), class = c("tbl_df", "tbl", "data.frame"))