Stocks opened higher on Monday after the Trump administration reached a deal with Mexico to end their dispute over the flow of migrants into the U.S. The S&P 500 /zigman2/quotes/210599714/realtime SPX +0.06% was up 0.4% to 2,885 The Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA +0.17% advanced 138 points, or 0.5%, to 26,122. The Nasdaq Composite /zigman2/quotes/210598365/realtime COMP -0.87% rose 0.7% to 7,797. President Donald Trump halted his plan to impose to tariffs on Mexican imports after striking a deal with that country to a range of measures aimed at reducing the level of immigration from Mexico. But Trump said he could bring tariffs back into play if Mexico didn't cooperate with the U.S. on border issues. Shares of United Technologies and Raytheon Co. both rose after they agreed to a merger that would create the world's second biggest aerospace company by revenues.