The resignation of former CEO John Stumpf from Wells Fargo is "not enough" to assuage lawmakers that the company has purged itself of a culture that encouraged aggressive sales tactics and illegal activity, two senators said Wednesday. Elizabeth Warren (D-Mass.) and Robert Menendez (D-N.J.) issued a letter Thursday to Stephen Sanger, who is the new chairman of Wells Fargo’s board of directors. “Given the scope of wrongdoing on his watch, Mr.