[Beijing Stock Exchange conducts optimization simulation tests for margin trading and other business] Fannie Mae, June 9 (Xinhua)-- the Northern Stock Exchange plans to carry out optimization simulation tests for margin trading and other business in the near future. The first round of simulation tests: June 12, 2023 to June 16, 2023. The second round of simulation tests: June 26, 2023 to June 30, 2023. The test environment is open all day from Monday to Friday.