In 1985, The Coca-Cola Company's share lead over its chief competitor Pepsi, in its flagship market, with its flagship product, had been slowly slipping for 15 consecutive years. In what was then a lethargic cola category, consumer preference and awareness for Coca-Cola was dipping. It was decided to change the fabled secret formula for Coca-Cola and to adopt a formula preferred in taste tests of nearly 200,000 consumers. What these tests didn't show, of course, was the bond consumers felt with their Coca-Cola -- something they didn't want anyone, including The Coca-Cola Company, tampering with.

New Coke was introduced on April 23, 1985. Production of the original formulation ended that same week. The American public's reaction to the change was negative and the new cola was a major marketing failure.

Company headquarters in Atlanta started receiving letters expressing anger or deep disappointment. Over 400,000 calls and letters were received by the company, including one letter that was addressed to "Chief Dodo, The Coca-Cola Company". Another letter asked for his autograph, as the signature of "one of the dumbest executives in American business history" would likely become valuable in the future. The company hotline, 1-800-GET-COKE, received 1,500 calls a day compared to 400 before the change. A psychiatrist Coke hired to listen in on calls told executives some people sounded as if they were discussing the death of a family member.

Coca-Cola executives announced the return of the original formula on July 10, less than three months after New Coke's introduction

The reintroduction of Coke's original formula, re-branded as "Coca-Cola Classic", resulted in a significant gain in sales, leading to speculation that the introduction of the New Coke formula was just a marketing ploy.

This "marketing blunder of the century" changed forever The Coca-Cola Company's thinking and the way marketers perceived brands. It was now realised that brands no longer belonged to the manufacturers but to the consumers.