SINGAPORE/HANOI -- Global investment firm KKR & Co has emerged as the largest shareholder of one of Vietnam's biggest eye hospital chains, Medical Saigon Group (MSG), according to an MSG internal memo seen by Reuters on Friday. Financial details of the investment were not disclosed in the memo sent to MSG's staff on January 19 from MSG Group Chief Executive Officer Huynh Le Duc. New York-based KKR will take over as MSG's largest shareholder from Singapore's investment firm Heliconia Capital, wholly-owned unit of Singapore's state investment firm Temasek Holdings, according to the memo. "KKR will step into the shoes of Heliconia to become our largest shareholder. KKR, which counts property group Vinhomes and education company EQuest among its investments in Vietnam, also invested in the Philippines' largest private hospital group Metro Pacific Health, according to its website.