Rubuta ci gaba ga wannan sakin layi - A 1875, ya shiga New York Stock Exchange kuma ya kasance memba na shekaru arba'in da hudu. Ya yi aiki a matsayin shugaban Exchange na shekaru biyar daga 1898 zuwa 1902. Duk da yake shi ne shugaban Exchange, da yawa daga cikin lokacin da aka sadaukar da shi zuwa ga dubawa da gina ginin a 11 Wall Street. Lokacin da aka kashe Shugaba William McKinley
a cikin 1901 a Buffalo yayin baje kolin Pan-American, "an ce cewa Mista Keppler mai ra'ayin mazan jiya da kuma amincewar da Wall Street ya yi masa sune mahimman abubuwan da ke hana firgita da kuma kwantar da hankalin tsoro". A shekara ta 1913, Samuel Untermyer ya yi masa tambayoyi a lokacin da ake kira Pujo Money Trust Investigation.