headquarters_location koscom
___MASK32___ ;, officially ___MASK32___ Metropolitan City (  ), romanized as Pusan before 2000 , is ___MASK54___ ' s second most - populous city after ___MASK40___ , with a population of approximately 3 . 6 million . The population of the metropolitan area , including the adjacent cities of Gimhae and Yangsan , is approximately 4 . 6 million . The city is located on the southeastern - most tip of the Korean peninsula . ___MASK40___ (  )  officially the ___MASK40___ Special City  is the capital and largest metropolis of the Republic of Korea ( commonly known as South Korea ), forming the heart of the ___MASK40___ Capital Area , which includes the surrounding Incheon metropolis and Gyeonggi province , the world ' s 16th largest city . It is home to over half of all South Koreans along with 678 , 102 international residents . Koscom ( acronym of Korea Securities Computing Corporation Korean :  , Koscom ) is a Korean financial IT solutions company launched by the Ministry of Finance ( MOSF ) and the Korea Exchange ( KRX ) in 1977 . It has five corporate divisions with providing IT infrastructure to the Korean financial securities and futures market . Koscom also offers online stock trading systems that enable users to access to financial database and place trades by Home Trading System or using a customized terminal for professional traders in securities as well as other electronic financial services . Major Korean financial firms have subscription to the Koscom ' s online trading services including market news , price quotes and financial market data . Korea Exchange ( KRX ) is the sole securities exchange operator in ___MASK54___ . It is headquartered in Busan , and has an office for cash markets and market oversight in ___MASK40___ .