0824 GMT - Gulf markets face pressure this week from potential tightening sanctions on Iran and elevated U.S. Treasury yields, Iridium Advisors says. The consultancy says details of what U.S. Treasury Secretary Scott Bessent has called the "toughest sanctions in history" could push negotiations with Iran further out of reach, while the U.A.E.'s halt to trade and financial transactions with Tehran may raise questions over corporate exposure to Iranian customers, suppliers and payments. Higher Treasury yields could also lift regional discount rates and borrowing costs, weighing particularly on real estate, utilities, infrastructure and telecom stocks.