HERBERT Hui did not mince his words when he took some merchant banks to task for failing to live up to their obligations to mainland companies listed in the territory. ''This is irresponsible'', the stock exchange listings chief said of the culprits who allegedly failed to honour their obligations to the Chinese companies once they were listed. ''You don't walk away when a company needs you to see it through the difficult transition from being a state-owned company to a publicly-listed one.'' Mr Hui's remarks were valid, but he stopped short of naming the culprits in public - which is a pity. Mr Hui cannot decide on his own to publicise the names. However, if the authorities have proof of unprofessional practices, there should be no reason why the names of the culprits should not be made public. It would be controversial, but reprimands by the Securities and Futures Commission are routinely published, together with names and details of the offences. More mainland state-owned companies will turn to Hong Kong for their fund-raising exercises in the next few years. So the role of the merchant banks as sponsors to Chinese companies seeking listings should not be underestimated. A listing is not just a fund-raising exercise. There are many continuing legal, financial and investor obligations - a fact sometimes not grasped by even some local companies, let alone Chinese state-owned firms making the transition to publicly-listed ones. That is where the sponsors come in. They are supposed to advise the Chinese companies on what to do before and after listing. This is clear from the outset, when they go chasing after the Chinese clients. There is no excuse for not meeting that obligation. Merchant bankers' sponsorship is even more important in one respect: that of educating these companies untrained in financial transparency and even accountability, to accept a much higher degree of market discipline. Clearly, it is not enough to have the extra requirement of a sponsor for Chinese companies for three years if merchant banks that fail to carry out their duty are not censured. The stock exchange may not have the clout to punish the culprits. But what about public censure?