Citing a breach of confidentiality rules, the company has agreed to a pay-off of $7.5m.
Lyons stepped into the CFO role when predecessor Shane Fitzsimons went on medical leave in January.
In a statement, AIG said:
"In recognition of Mr. Lyons’ contributions to AIG since he joined the Company in 2018, the Company entered into a settlement agreement with Mr. Lyons."
The statement also confirmed that he had not disclosed confidential information and that the violation of his confidentiality obligations related to 'the sharing of access to company-issued communication devices'.
Lyons has agreed not to sue AIG over the termination as part of the settlement.
AIG has appointed Sabra Purtill - currently chief investment office of AIG spin-off Corebridge - as its new interim CFO.
