US companies are one step closer to having to change the way they account for mergers and acquisitions, after a ruling by the Financial Accounting Standards Board (FASB), the US accounting watchdog.

The board met on Wednesday and voted unanimously to eliminate the &quotpooling of interests&quot accounting method. A debate has been raging in the US for several years over whether companies should effectively be able to make M&A deals look less expensive than they really are by using different accounting methods.