Treasury Secretary Janet Yellen alluded to what she saw as the significant dangers of a Trump administration.Alex Wong/Getty ImagesTreasury Secretary Janet Yellen criticized the prior administration often in a speech on Thursday.She didn't name Trump, but said his appointees rolled back key regulations to protect the economy.Yellen's remarks come as the economy is a key issue for everyday voters and private sector leaders.Speaking at the US Treasury Market Conference on Thursday, Treasury Secretary Janet Yellen referenced her predecessors — and their mistakes — often.