If you had asked me six months ago about the risks of another massive financial crisis in the United States, I would have said it is always possible, but much more likely elsewhere. Japan, for example, is dealing with steadily rising interest rates in an economy that has been conditioned for decades to rates being virtually zero.

But I seem to have underestimated the deregulatory zeal of President Donald Trump’s administration. While it is rightly rethinking the heavy-handed measures implemented after the 2008 Global Financial Crisis, it is ruthlessly pruning staff at key reg...