The new trade agreement between the U.S., Mexico, and now Canada is both a political victory for President Donald Trump and good news for the stock market.

At midday Monday, the major U.S. equity indexes were up, although off from their higher morning levels. U.S.-listed exchange-traded funds for the Canadian and Mexican markets also were trading higher, bolstered by lifts in their stock markets and currencies following news late Sunday of the new deal to succeed Nafta.

The...