Banco Nacional Ultramarino (Portuguese: Banco Nacional Ultramarino, literally translated as "National Overseas Bank") is a bank established by Portugal in its former colony. It was established in Lisbon in 1864 and was responsible for promoting the economic development of the Portuguese overseas territories. Later, it was also responsible for issuing banknotes from the Portuguese colonies. Banco Atlantico's operations have spread all over the world, especially in Portugal's former overseas provinces. After its merger with the government-owned Portuguese Savings and Credit Bank (Portuguese: Caixa Geral de Depósitos) in 2001, Banco Atlantico ceased to be a separate legal entity in Portugal. The current Banco Atlantico, as a branch of Banco Nacional de Depósitos in Macau, maintains the original Portuguese and Chinese names.

The Macau branch of Atlantic Bank is headquartered in the main road (Xinma Road) of Libero, Armenia. Its building was built in 1926, and the outer wall of the original building was retained when it was expanded in 1997. The bank has a total of 20 branches, of which 14 are located on the Macau Peninsula, 4 are located in Taipa, 1 is located in Coloane, and 1 is located in the Guangdong-Macao Deep Cooperation Zone in Hengqin, Zhuhai. It also has a representative office in Shanghai.

National Overseas Bank, which is translated into Chinese as Atlantic Bank, was established in Lisbon, the capital of Portugal, in 1864. Branches were opened in Angola and Cape Verde in 1865, and in Sao Tome and Principe and Mozambique in 1868. The Macau branch was established in 1902, the same year as Guinea-Bissau. The East Timor branch was established in 1912. After opening branches in the colonies of Africa and the East, the Bank of the Atlantic began its second phase of expansion in 1917, establishing a network of branches in mainland Europe, Madeira and the Azores, forming the largest Portuguese banking network.

The banknotes issued by the Bank of the Atlantic are a milestone in the history of currency circulation in the former colonies, as they were able to gradually regulate the circulation of money, end the wide variety of currencies in circulation locally and become the only legal tender. Bank of the Atlantic banknotes are issued in different currency units, including the escudos in Angola, Mozambique, Equatorial Guinea, Sao Tome and Principe, East Timor, the pataca in Macau, the escudo and rupee in Goa, India, etc., depending on the time and space of their circulation. In the former colonies of the East - India, Macau and Timor - the issuance of Atlantic Bank followed the sovereignty of Portugal over them: in India until 1961, in Timor until 1975.

Until the 1960s, Atlantic Bank was the bank with the largest branch network in Portugal. After the April 25 Revolution in 1974, the new government pursued a policy of nationalization, and Atlantic Bank was nationalized in the same year. According to the terms of the agreement concluded between the Portuguese government and the governments of the then independent New Portuguese-speaking countries, Atlantic Bank transferred the assets and liabilities of all its subsidiaries to the newly established Bank of the former colonial countries. In 1988, Banco Atlantico was partially privatized, with Banco Sanco de Credit Portugal holding 99% of Banco Atlantico's share capital as the bank's largest shareholder, with the remaining 1% belonging to the Portuguese national government. On March 28, 2001, Banco Atlantico and Banco Sanco de Credit Portugal announced their merger, and Banco Atlantico became a wholly owned subsidiary of Banco Sanco de Credit Portugal. The Macau branch of Banco Atlantico was changed to a local bank registered in Macau, and the original name remained unchanged

Banco Atlantico established a branch in Macau in 1902, which was the first bank in Macau. In the early days of its establishment, the Chinese name was "Atlantic Overseas Bank of Portugal". For a brief period in the 1960s, the Chinese name was changed to "Portuguese Overseas Bank".

The Macau branch of Bank of the Atlantic began to be responsible for the issuance of banknotes in patacas in 1905. During the period of Portuguese rule, Macau did not have a complete financial regulatory framework; until Bank of the Atlantic established a branch in Macau in 1902, it became the first bank in Macau. After the third anniversary of its establishment (1905), it was entrusted by the government to become the first Financial Institution Group to issue banknotes in Macau. Since then, the local political and economic environment in Macau has undergone profound changes, and the overall situation has continued to develop. At that time, Bank of the Atlantic, as the only bank with the right to issue banknotes and acting as the cashier's agent for the public treasury of the Macao government, actually played the role of a quasi-central bank. Until 1980, the banknote-issuing rights of Atlantic Bank were taken back by the government and transferred to the Macau issuing institution (the predecessor of the Macau Monetary Authority). After that, Atlantic Bank continued to issue banknotes, but only acted as the agent of the Macau issuing institution by signing an agency contract.

Atlantic Bank Macau Branch began to be responsible for the banknote-issuing work of the Macau dollar in 1905. It was the only banknote-issuing bank in Macau until 1995. In addition, Atlantic Bank Macau Branch was also the only cashier agent bank for the Macau government's public treasury until 2000. Together with Bank of China Macau Branch, it served as the cashier agent bank for the Macau government's public treasury until 2000.

On January 18, 2017, Atlantic Bank opened a Hengqin branch in the Hengqin New Area of Zhuhai, China (Guangdong) Pilot Free Trade Zone, becoming the first local bank in Macau to open a branch in the Chinese mainland.