SP500 package:MASS R Documentation _R_e_t_u_r_n_s _o_f _t_h_e _S_t_a_n_d_a_r_d _a_n_d _P_o_o_r_s _5_0_0 _D_e_s_c_r_i_p_t_i_o_n: Returns of the Standard and Poors 500 Index in the 1990's _U_s_a_g_e: SP500 _F_o_r_m_a_t: A vector of returns of the Standard and Poors 500 index for all the trading days in 1990, 1991, ..., 1999. _R_e_f_e_r_e_n_c_e_s: Venables, W. N. and Ripley, B. D. (2002) _Modern Applied Statistics with S._ Fourth edition. Springer.