NEW YORK (CNNMoney.com) -- Struggling insurance giant America International Group owes Wall Street firms $10 billion from trades that went sour, according to sources cited by The Wall Street Journal.

AIG (AIG, Fortune 500), which is now operating under government assistance, had not previously detailed these losses, which stemmed from speculative investments in mortgage and corporate debt assets, the Journal wrote on Wednesday. And now that those investments have gone south, the company must pay off its investment partners.

However, the Journal reported that an AIG spokesman told the paper that AIG defines the trades not as speculative but as "credit protection instruments." The spokesman also said the company believed it had already disclosed the exposure.

The government's $150 billion rescue package doesn't cover these losses, which raises questions about how AIG will pay off the debts, according to the Journal.