Text ３ 　　Twelve months ago, Lululemon Athletica was one of the hottest brands in the world. Sales of its high-priced yoga gear were exploding; the company was expanding into new markets; experts were in awe of its “cultlike following.” As one observer put it, “They’re more than apparel. They’re a life style.” But then customers started complaining about pilling fabrics, bleeding dyes, and, most memorably, yoga pants so thin that they effectively became transparent when you bent over. Lululemon’s founder made things worse by suggesting that some women were too fat to wear the company’s clothes. And that was the end of Lululemon’s charmed existence: the founder stepped down from his management role, and, a few weeks ago, the company said that it had seen sales “decelerate meaningfully.” 　　It’s a truism of business-book thinking that a company’s brand is its “most important asset,” more valuable than technology or patents or manufacturing prowess. But brands have never been more fragile. The reason is simple: consumers are supremely well informed and far more likely to investigate the real value of products than to rely on logos. “Absolute Value,” a new book by Itamar Simonson, a marketing professor at Stanford, and Emanuel Rosen, a former software executive, shows that, historically, the rise of brands was a response to an information-poor environment. When consumers had to rely on advertisements and their past experience with a company, brands served as proxies for quality; if a car was made by G.M., or a ketchup by Heinz, you assumed that it was pretty good. It was hard to figure out if a new product from an unfamiliar company was reliable or not, so brand loyalty was a way of reducing risk. As recently as the nineteen-eighties, nearly four-fifths of American car buyers stayed loyal to a brand. 　　Today, consumers can read reams of research about whatever they want to buy. This started back with Consumer Reports, which did objective studies of products, and with J. D. Power’s quality rankings, which revealed what ordinary customers thought of the cars they’d bought. But what’s really weakened the power of brands is the Internet, which has given ordinary consumers easy access to expert reviews, user reviews, and detailed product data, in an array of categories. 　　A recent Pricewaterhouse Coopers study found that eighty percent of consumers look at online reviews before making major purchases, and a host of studies have logged the strong influence those reviews have on the decisions people make. The rise of social media has accelerated the trend to an astonishing degree: a dud product can become a laughingstock in a matter of hours. In the old days, you might buy a Sony television set because you’d owned one before, or because you trusted the brand. Today, such considerations matter much less than reviews on Amazon and Engadget and CNET. As Simonson told me, “each product now has to prove itself on its own.”