The global financial crisis, highlighted by the collapse of Lehman Brothers, the sale of Merrill Lynch and the bailout of AIG, has wiped $50bn (£27.4bn) off the value of the top global brands in the first weeks of September.

A report by Brand Finance for MediaGuardian.co.uk, which also covers tumultuous events such as the US bailout of Fannie Mae and Freddie Mac and Lloyds TSB's potential takeover of HBOS, reveals just how badly the top 100 global brands have been hit.

Brand Finance published a report on Wednesday showing that it had taken eight months, until the end of August, for a total of $67bn to be stripped off the brand value of the top 100.

The new report shows that $50bn has been wiped off so far in September, 80% of which was in the financial services giants.

Brands hit include Citibank, Goldman Sachs, JP Morgan, UBS and AIG. Others hit include Deutsche Bank and Credit Suisse.

Bank of America, which bought Merrill Lynch following a crash in its shares, has retained brand value, while HSBC has remained resilient.

"HSBC is an interesting example of a company that has really focused on its brand, it stands for something with consumers," said Oliver Schmitz, the UK managing director at Brand Finance.

"Some say it is time to focus on the business basics but it is also a time where customers need to rely on brands."

He cited Virgin and Vodafone as examples of "brand companies" that rigorously manage their brand image globally, while many other companies have a more piecemeal approach in different markets.

Schmitz said that retail was the the only sector that has not seen a decline in the past few weeks.

Companies such as Wal-Mart and rival Target, which offer consumers value-for-money deals that appeal in leaner times, had actually increased in brand value.

Coca-Cola was another example of a brand that has remained strong.

"Generally the top brands are so successful because they aren't as susceptible to the volatility of the financial markets or rapid swings in the public's favour," he said.

Schmitz added that there had been slight decreases in the brand value of Apple, partly because customers may shy away from more expensive non-core services, and Google, over factors such as the as yet unknown impact of its web browser Chrome.

Luxury brands such as Gucci and Louis Vuitton remain strong because they are highly aspirational, he said, but as not all of their customers are recession proof, their brand value is likely to fall as revenue forecasts are hit.

"We think that coming out of the other side of the economic downturn brands from emerging markets such as Tata [the Indian automotive-to-coffee and mineral water giant] may be able to capitalise on their position by improving and globally marketing their brands," Schmitz said.

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