It is the end of an era for Coca-Cola. Some 114 years after Dr John Styth Pemberton first concocted the drink in the basement of his Atlanta home, its decades of supremacy as the world's most valuable brand seem about to draw to a close. In a moment that may come to symbolise the new economy's triumph over the old, a study published during the week, shows that Coca-Cola has held on at the top of the global league table from Microsoft, a name invented only 25 years ago, which increased its brand value by almost a quarter despite a turbulent year.

Its rankings show that CocaCola is not the only old economy brand to have lost value as new economy brands have gained. Some of the worst performers in the league table are Kodak, Heinz, Xerox, Wrigley's, Hertz, Burger King, Johnnie Walker, Guinness and Pampers, all of which show declines. Nearly all the brands that have lost value in the rankings belong to companies in the food, drink or consumer packaged goods businesses. The Coca-Cola brand is still reckoned to be worth a phenomenal $72.5 billion (€61.33 billion) in terms of its earnings potential. But its value has tumbled 13 per cent in the last year, while the value of Microsoft's brand is estimated to have increased 24 per cent to $70.2 billion. At that rate, Microsoft is within weeks of overtaking CocaCola as the world's most valuable brand, if it has not already done so. And since the US Justice Department is unlikely to succeed in its efforts to break up the Microsoft company in the next year or so, the Microsoft brand seems almost certain to top the rankings next time.

The evidence of Microsoft's looming supremacy comes from Interbrand, the branding consultancy, which is in its second year of analysing earnings forecasts for the world's best-known consumer brands and translating those forecasts into brand valuations. Other poor performers amongst traditional high-profile brands include Procter & Gamble, which has issued three profit warnings this year and recently ousted its chief executive. The combined value of the group's brands, which include Tide, Pampers and Crest, is estimated to have fallen by 2 per cent to $48.3bn. In contrast, most new economy brands show double-digit percentage gains in value, and technology companies now account for four of the top five brands. The only loser is Ericsson, whose value is estimated to have plunged 47 per cent - reflecting the success of Nokia, its biggest rival.

Even so, dotcom companies have yet to make much impact on the league table because few have global scale or foreseeable earnings. As last year, the only online brands in the rankings are Yahoo , AOL and Amazon.com. Interbrand said it was not concerned by analysts' reports questioning Amazon's viability because the brand would probably survive if the company did not. Although Coca-Cola still heads the rankings, its rapid decline in value is remarkable for a brand that once looked unassailable. Only a year ago, Interbrand calculated that the name was worth $83.8 billion - way ahead of Microsoft in second place, with an estimated value of $56.7 billion. Even as the league table was published, however, it was being overtaken by events. Coca-Cola had badly fumbled a headline-hitting contamination scare in Europe, and the company was being accused of arrogance and indifference.

That was only the start of one of the worst periods in Coca-Cola's history. Profits were affected not only by a massive product recall in Europe, but by weak sales in the US and elsewhere. European regulators blocked planned acquisitions and started an antitrust investigation; black employees launched a racial discrimination lawsuit; the company's slumping stock price led to the resignation of Douglas Ivester as chief executive only two years into the job; and Mr Ivester's replacement, Douglas Daft, announced that 6,000 employees would go in the company's biggest job cuts. If all that were not bad enough, even more troubling factors were at work - affecting not only Coca-Cola, but also other old economy owners of consumer packaged goods brands. Stock market investors had long been aware that demand for packaged goods was relatively mature in developed countries. But in the bull market of the 1990s, many became seduced by the idea that companies such as Coca-Cola and Procter & Gamble could look forward to seemingly limitless growth in the world's emerging economies.

With the collapse of communism and the lifting of barriers to global trade, multinational companies could now market their products to billions of new consumers who, it was assumed, were desperate to mimic their cousins in the developed world by adopting western brands. But this assumption proved to be over-optimistic. In fact, multinational companies were disappointed to find that indigenous brands evolved with surprising speed, and that many people preferred them to western ones - especially when, as was often the case, they were much cheaper. Local companies were also at a big advantage in knowing how to do business in their own countries, leaving multinationals heavily dependent on local partners. And multinationals often found themselves competing not only with indigenous brand owners, but also with other multinationals prepared to pay almost any price to establish themselves in these new markets.

By the end of last year, most consumer goods companies had seen their stock prices plummet as these realities sank in. The downward revision in estimates of the companies' growth prospects explains why their brands are among the weakest performers in this year's league table. The food, drink or consumer packaged goods sectors account for many of the lowest gainers: McDonald's, Marlboro, Gillette and Kellogg's, for example, all saw relatively small increases in brand value. So did Nestle, Unilever and Diageo, with their big portfolios of mature brands. The outlook for companies such as these is troubling, as their problems are not confined to emerging markets: they are getting worse at home. The reason is that, in developed countries, most basic consumer needs have been met, so it is becoming increasingly difficult to invent new products. At the same time, categories are experiencing an onslaught of competition from ever-proliferating copycat products and supermarket own-label goods.

Brand owners hope that as people become increasingly confused by the product proliferation, brands will become the beacons that guide them through the confusion of endless choice. But while this may turn out to be the case, it seems just as likely that people will increasingly regard basic consumer goods as commodities and buy whatever happens to be cheapest, saving their brand preferences - and money - for more exciting products such as mobile phones or fashionable clothes.

Until now, companies such as Coca-Cola, H.J. Heinz and Kellogg had been around so long that their brands looked indestructible, and seemed destined to command the top slots in the global league table for as long as anyone could foresee. It is still hard to imagine a day when these famous names will cease to dominate the supermarket shelves. But when a brand as powerful as Coca-Cola can lose 13 per cent of its value in just a year, it is possibly time to ask whether the lifespan of these brands is infinite, or something less.