Wall Street is already weighing potential market impact of a Trump presidency

With the U.S. presidential election still more than nine months away, Wall Street is weighing in on the possibility of a Donald Trump return to the White House and is mapping out the potential reactions that could unfold in financial markets.

As Trump faced off with challenger Nikki Haley in the New Hampshire Republican primary on Tuesday, Dominic Wilson and Vickie Chang of Goldman Sachs GS, -1.80% looked back to the market reaction seen from the results of last week’s Iowa caucuses. In particular, they zeroed in on a...