Grupo Aeroportuario Centro Norte, S.A.B. de C.V., known as OMA, is a Mexican airport operator headquartered in San Pedro, near Monterrey, Mexico. It operates 13 airports in the central and northern states of Mexico, including that of Monterrey, one of Mexico's largest cities. It is the fourth largest airport services company by passenger traffic in Mexico. It serves approximately 15 million passengers annually. OMA is listed on the Mexican Stock Exchange and in the NASDAQ through ADRs since 2006. In June 2015, OMA announced it had engaged UBS as market maker to promote the liquidity and trading volume for the shares listed on the Mexican Stock Exchange. Wikipedia