In response to the letter, Hancock said the company was taking steps to "reposition."
"AIG maintains an open dialogue with all our shareholders and welcomes their feedback and ideas," he said. "We have taken important and significant steps to reposition AIG by both simplifying and de-risking the company, and realizing attractive valuations from non-core asset sales. We remain on course and are determined to continue and accelerate these efforts. We look forward to sharing our progress and strategies at our regularly scheduled earnings call on Tuesday."
The company is scheduled to report quarterly results on Monday after the market close.
AIG is one of the largest insurance companies in the country.