<p>The stock market, take-over bidders, executive pay setters, perhaps Stephen Littlechild himself, even last summer's weather, all seem to have been undermining RPI-X price-cap regulation. Until recently, price-cap regulation was regarded as demonstrably superior to US-style rate-of-return regulation, and regulatory reform in several countries has embraced price-cap regulation. But in Britain, where price-cap regulation originated, the case now appears to be less compelling: price-cap regulation is perceived by some as conferring unwarranted profits on the utilities and imposing unsustainable demands on regulators. As a consequence, many people believe that we are slipping inexorably into some form of profit regulation. </p>