In captive reinsurance, life insurance companies transfer risk to entities affiliated with their business in overseas jurisdictions or U.S. states with light-touch rules, which allows them to free up regulatory capital.
Benjamin Lawsky, the New York Superintendent for Financial Services, has stopped issuing licenses for such activity, which he called "shadow insurance," while Vermont and Delaware still actively court the business.
In an apparent effort to reduce some scrutiny, MetLife last year announced it would merge three of its life insurance companies and a Bermuda-based captive reinsurance unit into one U.S.-based company, to "address regulatory concerns about the use of captive reinsurance."
Another point regulators have looked into is securities lending.
Insurers hold huge portfolios of stocks and bonds that they often lend out, typically to broker-dealers or hedge funds, backed by collateral, in return for a small fee.
This is generally seen as a low-risk activity, but played a key role in the near-collapse of AIG, which was reinvesting much of its collateral in often complex and risky instruments that rapidly lost their value when the crisis hit.
Insurers say such risky behavior is a thing of the past, yet they continue to lend out considerable amounts of securities. MetLife's securities lending portfolio ended 2013 at $28 billion, according to Moody's Investors Service.
Lastly, regulators are wary about a possible run on an insurer much in the same way as on a bank. The industry is fiercely contesting this perception, saying their business model is different, and funding more stable.
But the Federal Insurance Office, a Treasury unit that monitors the industry, last year pointed out that AIG was not the only U.S. insurer in trouble. Insurers Hartford Financial Services and Lincoln National both received taxpayer aid during the crisis.