Credit: AIG

Since he took the helm at American International Group (NYSE:AIG) in 2009, CEO Robert Benmosche has been a constant force driving the megainsurer back to its former glory. But with his announcement that he will retire in early 2015, some investors may begin to worry the progress will erode once Benmosche is gone.

Here are the top three reasons why those fears are unfounded.

1. Back to basics
Since its near collapse in 2008, AIG has been systematically shedding non-core businesses and investments -- returning its focus to pure insurance functions.With all of that work under his belt, Benmosche has just one piece of the puzzle remaining: International Leasing Finance Corp.

With the sale of ILFC to AerCap Holdings (NYSE:AER) scheduled to close during the second quarter this year, Benmosche will be leaving a centered, focused company to his successor. Though that's not saying the company will be a simple operation to run.

The business is a "very large, complex" one, stated Benmosche in his recent interview on Fox Business Network's Opening Bell, adding it will be of the utmost importance any candidate recognizes the complexities and risk management at work within the firm. But he also acknowledged a strong foundation to work from, with successful progress in updating risk management tools, big data analysis, and strong market presence.

2. Very Important
Though the company will face added scrutiny from regulators down the road, thanks to its systemically important designation, Benmosche is confident the company is up to the task.

Thanks in part to the government's ownership from 2009 to 2012, AIG and its management team has worked hand in hand with Federal Reserve regulators to develop a strong system of financial checks. With that system, and knowledge of the Fed team it will be working with, AIG and its investors have little to fear from the increased oversight.

With all of that groundwork in place, investors can be certain the company's strength will allow it to continue paying out dividends and completing share buybacks in the future.

3. Deep benches
Though the company is currently seeking out candidates from both internal and external sources, AIG remains one of the best staffed insurers in the country.

The insurer already demonstrated its deep benches in 2013 after rival Berkshire Hathaway poached four top executives to start a new line of excess liability operations. This should leave both Benmosche and investors confident whoever takes the helm will be backed by a team of managers and staff that's experienced within the market and within the very large, complex operations of AIG itself.

Don't panic
It's always a little sketchy when a top performing CEO makes his way out the door. But for AIG investors, Robert Benmosche's exit shouldn't create any lasting fear the company won't thrive after the transition. From its core businesses, its strong regulatory relationships, and its key employees, AIG is poised to continue growing, even without the man that steered it through the financial crisis and aftermath.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.