President Trump late last week signed an executive order laying out his “core principles” for regulating the U.S. financial system, and giving the head of the Treasury Department 120 days to detail how the current massive regulatory regime measures up. Trump’s core principles include fostering informed consumer choices, preventing bailouts, promoting economic growth, tailoring regulations and ensuring regulatory accountability. The broadly-worded order specifies, “Nothing in this order shall be construed to impair or otherwise affect ... the authority granted by law to an executive department or agency, or the head thereof.” The order was...