When accounting gets interesting, it is generally bad news. The latest example: the biggest China-based, US-registered auditors may be temporarily barred by the Securities and Exchange Commission for refusal to hand over audit papers held in China. This could hit Chinese companies’ valuations, if they are forced to list elsewhere, and investors could lose a lot of data.

The auditors at risk of a six-month practice ban include the Chinese affiliates of the Big Four (networks of partnerships with limited central control). They audit most of the big Chinese companies listed in the west. The auditors say the market value of companies affected is as much as $870bn, $464bn of which is US-listed. The SEC dismisses that figure, but has not offered its own. If the ban comes before the 2013 filing deadline, the disruption could be severe.

Chinese companies list in the US for various reasons, although high valuations and validation in the world’s biggest capital market are the most important. The most-traded US-listed Chinese groups have traded on an average 18 times expected earnings in the past five years. Hong Kong’s China-heavy Hang Seng index, the main alternative for many US-listed companies, has averaged 12.