For years, the supermarket business was a cosy duopoly, run by offshoots of two of Hong Kong's biggest companies. While there were other small-scale chains, ParknShop and Wellcome had a 70 per cent share of the market. Subsidiaries of Hutchison Whampoa and Jardine Matheson's Dairy Farm respectively, the power of their parent companies ensured access to prime sites and gave them unrivalled clout. A Consumer Council report found prices of many staple products differed little between the two chains. It detailed a system called retail price maintenance, under which minimum prices are agreed with suppliers. When French giant Carrefour tried to undercut these, it was blacklisted. Now there are signs this long-standing duopoly may finally be falling apart. So-called 'price wars' between the two chains have occurred many times before. But, in most of those cases, prices remained remarkably similar. This latest outbreak looks like it could be different. That is not so much due to the headline-grabbing price cuts on 1,000 items unveiled by ParknShop yesterday. Rather it is because of the promise to beat any prices offered elsewhere, and refund double the difference. The Consumer Council is right to urge caution, given past experience of price wars that failed to live up to expectations. But if such promises do not prove full of loopholes, then the era of limited competition should be over. Is it not difficult to see the catalyst behind this? However hard they try to deny it, the huge success of AdMart, the new cut-price grocery delivery service run by media tycoon Jimmy Lai Chee-ying, has clearly unnerved the supermarket chains. Times are changing and the rise of the Internet means rivals no longer need a bricks-and-mortar presence. Nor need it be long before the effects spread beyond this industry. Internet banking is still in its infancy. In time, it will provide an alternative to a local banking sector which is still less than fully competitive. Other local cartels would do well to watch out. In the past, they were protected by their business might and the reluctance of the Government to get involved. But technology is proving to be a powerful force for change, and is already beginning to bring the first benefits for consumers.