Hyderabad is the largest contributor to the Andhra Pradesh state's GDP, state tax and other revenues. As of 2011, the per capita annual income of Hyderabad was 44,300 (US$801.83). As of 2006, the largest employers in the city are the Governments of Andhra Pradesh (113,098) and Governments of India (85,155) employees. The World Bank Group ranked the city as the second best Indian city for doing business in 2009. In 2010, the economic analysis group GaWC ranked Hyderabad in its third tier (Gamma+ World City) of cities by importance. Hyderabad and its suburbs house the highest number of special economic zones among India cities.
Hyderabad is known as the "City of Pearls", due to the presence of pearls trading industry—until the 18th century the city was the only global trade center of large diamonds. Many traditional and historical bazaars are located in the city. The Laad Bazaar and nearby markets have shops that sell pearls, diamonds and other traditional ware and cultural antiques. The commercial market structure of Hyderabad is defined into 4 sectors—The Central Business Districts (CBD), the sub-central business centers, the neighborhood business centers and local business centers. According to a survey in 2007, the retail industry in Hyderabad had been growing along with traditional markets. and several central business districts are spread across the city.
During Nizam's rule in the 1930s industrialization was started, which was helped by expansion of railways, connecting the city with major ports of the country. From 1950s to 1970s, several Indian public enterprises were established in the city, such as Bharat Heavy Electricals Limited (BHEL), National Mineral Development Corporation (NMDC), Bharat Electronics (BE), Electronics Corporation of India Limited (ECIL), Defence Research and Development Organisation (DRDO), Hindustan Aeronautics Limited (HAL), Andhra Bank (AB) and State Bank of Hyderabad (SBH). This changed the economic pattern
