PRICES failed to sustain earlier gains yesterday, sagging under the influence of profit-taking on Wall Street to close lower. The blue-chip Financial Times Stock Exchange 100-share index, which slipped 2.4 points on Thursday, closed 2.7 points easier at 2,843.2 points. The narrower FT-30 index was down 1.4 points to 2,229.3 points. Volume was moderate with 542.2 million shares traded. Having been 12 points higher at one point in the session, the key FTSE turned lower in afternoon trading. Transport company Tiphook's shares fell sharply as it announced that its results would include significant changes to accounting policies, principles and interpretation, which will bring the company's reporting more closely in line with US accounting principles. Dealers took the view that the new policy would prune profits. Electricity stocks were the strong point of the market. The utilities were cheered by the release of a regulator's report that was less stringent than expected. In his first review of price controls for regional electricity companies since privatisation, Professor Stephen Littlechild, director general of electricity supply, slightly tightened price controls, but share prices moved ahead.