FOUR former vice-chairmen of the Stock Exchange were refused full costs for an eight-month corruption trial because their conduct had brought suspicion upon themselves, a High Court judge ruled yesterday. Mr Justice Mortimer held that accepting shares in newly listed companies while sitting on the listing committee approving such listings led almost inevitably to their prosecution. All four were acquitted. Mr Charles Sin Cho-chiu, 56, is to get one fifth of his costs because the Crown did not ask the jury to return a verdict on one of the five counts he faced. Mr Cham Siu-leun, 70, is to get one sixth of his costs up to the first day of trial, when the Crown dropped one count against him. Mr Kenneth Wong Kai-ming, 61, and Mr Joseph Ma Ching-chung, 54, have to bear the whole cost of their defence. Mr Wong and Mr Cham brought out a London barrister for the three-day application for costs. Costs for the four are estimated to run into tens of millions of dollars. After the hearing, Mr Sin would only say his costs were ''a very substantial amount''. He would not comment on the judge's ruling. In the ruling, the judge said defendants were entitled to costs unless there was a positive reason for not doing so. He said he had to consider the defendants' conduct in the knowledge that each had been acquitted and therefore their conduct was not criminal. As vice-chairmen, they were senior members of the committee which was the mind and will of the Stock Exchange. Each was on the all-powerful listing committee. The distribution of shares, placements and sub-underwriting was made to the defendants not as individuals, but in their capacity as vice-chairmen. Their control over the exchange had implications for the financial sector in Hongkong, the judge said. This, he found, was a positive reason why he should exercise his discretion not to award costs. He said the case of the four applicants could be distinguished from those of Mr Alfred Li, a legal adviser to the Stock Exchange, and former chief executive of the Stock Exchange Mr Jeffrey Sun Hon-kuen, who were awarded costs. In Mr Li's case, the jury was never asked to consider his case, and he was acquitted on the direction of the judge. Once Mr Sun's conduct was to be regarded as not criminal, the judge said he must be regarded as following the instructions of the Stock Exchange. He stressed that his ruling had no implications beyond the costs application, saying each defendant has been completely and irrevocably cleared of any criminal behaviour. ''Each came to court with a high reputation for integrity and public service. That reputation remains completely intact,'' he said. The judge directed that inquiries be made to the Legal Department on what action had been taken over a newspaper article which could have led to the trial being aborted. The matter was raised by Mr Michael Sherrard QC, for Mr Sin, who said it was believed the publication had not come to the attention of the jury, otherwise the trial may well have been aborted. He said it was a serious matter and the court did not want to give the impression that the matter was forgotten.