The value of IBM's(IBM) brand has declined by 13% over the past year, pushing it down one rank to fourth place.
Cheung said the tech firm's brand has foundered as IBM tries to compete in the cloud computing space against the likes of Amazon(AMZN) and Microsoft(MSFT).
Lower profitability has also dragged down the overall valuation, she said. In the most recent quarter, IBM reported results that missed Wall Street's expectations.
"We are disappointed in our performance," CEO Ginni Rometty said when the results came out.
First published May 27, 2015: 4:11 AM ET
Methodology: This 2015 BrandZ ranking of the most valuable brands in the world was carried out by brand consultancy Millward Brown, which is part of the advertising firm WPP. It calculates brand value by using in-depth financial data alongside interviews with over three million consumers from around the world.
