All five defendants were found guilty in February of conspiracy and fraud after they allegedly boosted AIG's profit loss reserves to mislead investors and artificially inflate the company's share price, Reuters said.
Prosecutors argued that their actions cost AIG's backers as much as $1.4 billion but US district judge Christopher Droney instead ruled that the damage was between $544 million and $597 million.
Losses incurred by victims of financial crime are a central factor in determining sentencing, Reuters added.
Douglas Berman, a law professor at Ohio State University, told the site that the judge's figures would lead to sentencing guidelines "of at least decades".
Among those awaiting sentencing are General Re's former chief executive Ronald Ferguson, the company's former financial officer and AIG's former vice-president of reinsurance, Christian Milton.