A book published yesterday states that a company's market value is less closely related to book value than was the case historically.

Cracking the Value Code: How Successful Businesses Are Creating Wealth in the New Economy argues that the majority of public companies' stock-market value is derived from assets which never appear on balance sheets - things like knowledge, brands, innovation, people and relationships.

The book is published by Arthur Andersen and is based on a three-year study of 10,000 public companies.