Deal worth up to $32m shows foreign brokerages following investment firms into country Mirae Asset will discuss further cooperation with Okasan Securities, including selling exchange-traded funds to Okasan customers. (Mirae Asset Securities) TOKYO -- South Korea's Mirae Asset Securities will begin proprietary stock trading in Japan with the acquisition of a brokerage owned by Okasan Securities, Nikkei has learned, as foreign financial firms see opportunities in the country's stock market boom.