Tyco inquiry finds no major fraud

The review, conducted by a law firm, concluded that accounting tricks had been used to inflate Tyco's earnings by nearly $400m (£248m) in 2002.

The investigation found that shoddy records and inadequate policies existed when Dennis Koslowski was the chairman.

"There were also instances where senior management exerted pressure and provided incentives which had the purpose and effect of encouraging unit and segment officers to achieve higher earnings, including in some cases by their choice of accounting treatments," the report said.

Silver lining?

Tyco's shares have been battered this year after Mr Koslowski and chief financial officer Mark Swartz were charged with stealing hundreds of millions of dollars from the company.

Both men have pleaded innocent.

Brett Truman, professor of accountancy at Haas Business School in California, told the BBC's World Business Report that investors would be cheered by the investigation's findings.

"When a company engages in fraud, that often means that they've exhausted the more legitimate means to manipulate their income upward," he said.

"The fact that they have not engaged in much fraudulent accounting at all probably says that the company's management doesn't believe that Tyco is in such bad straits that they had to resort to such behaviour."