Former Macquarie equities broker Newton Chan pleaded guilty in the Supreme Court of Victoria on Friday to eight charges relating to the alleged manipulation of the Bill Express share price between 2006 and 2008.The court was told that Chan was not the architect of the scam that involved buying and selling more than $6 million worth of BXP stock at the beginning and near the end of trading days.The manipulation of the share price was designed to avoid margin calls being made against directors of Bill Express and related companies.The court has been told that Chan has agreed to give evidence against his co-accused.Enzo Di Donato will be required to enter a plea on similar charges when he next faces court in July, according to a spokesperson for ASIC.ASIC is also believed to be investigating a number of large transactions that were made by Bill Express on or just before financial reporting dates.A number of former Bill Express directors and executives, as well as their auditors from KPMG, have been quizzed by ASIC investigators about the purchase and sale by Bill Express of a product known as SIMEX stock, the Supreme Court has heard.