"The U.S-Thai Treaty of Amity, formally known as the Treaty of Amity and Economic Relations, was signed at Bangkok on May 29, 1966. The treaty allows for American citizens and businesses incorporated in the U.S, or in Thailand to maintain a majority shareholding or to wholly own its company in Thailand, and thereby engage in business on the same basis as would a Thai national. These companies are also exempt from most of the restrictions on foreign investment imposed by the Foreign Business Act of 1999. The treaty in effect allows for an equality of benefits between the countries. American companies who wish to be covered by the Treaty of Amity should have a minimum of 50% American directors and a minimum of 51% of shares must be held by American citizens.
Under the U.S.-Thai Treaty of Amity, Thailand restricts American investment only in the following fields of business:
The treaty also allows for preferential treatment for Thai businessmen applying for visas to conduct business in the United States. The formalities for their applications are kept to a minimum. Under the treaty the U.S. Congress may not enact discriminating laws against Thai firms. Their profits may be freely remitted to Thailand and their assets may not be expropriated."
Source: Wikipedia on the treaty of Amity