** Shares of payments firms Capital One COF.N and Discover Financial Services DFS.N rise 11.5% and 10% premarket, respectively, after Republican Donald Trump elected U.S. president

** Companies are awaiting approval for their $35.3 bln merger deal, which was unveiled in February

** Analysts expect a looser antitrust environment under Trump, who is expected to overhaul the country's financial regulators, many of which have unveiled stringent rules for banks and M&As in the last few years

** Last month, New York Attorney General Letitia James said she was investigating if the Capital One-Discover deal violates the state's antitrust law

** Rivals American Express AXP.N, Visa V.N and Mastercard MA.N gain 4.6%, 3.6% and 2.4%, respectively

(Reporting by Niket Nishant in Bengaluru)

((Niket.Nishant@thomsonreuters.com))