For his first year in office, investors saw President Donald Trump as a boon for the stock market. But lately? Not so much.
Mr. Trump’s election confronted investors with competing narratives. On the one hand, his victory ratcheted up political uncertainty. He lacked policy experience, his plans were only lightly sketched out and his views on some matters, such as trade, were anathema to markets. But on the other hand, a Trump presidency and a Republican-controlled Congress held out the possibility for substantial tax cuts,...