The global financial system remains "overly complex" as reforms bog down in the post-recession economic slump, the IMF warned in a report Tuesday.
And central banks' record-low interest rates may be creating future problems by encouraging excessive risk taking, the very behavior that reforms are trying to curb, the International Monetary Fund said in its latest Global Financial Stability Report.
The IMF said that financial systems were little changed five years after the start of the US subprime mortgage crisis that plunged the global economy into recession.
"The data suggest that financial systems are still overly complex... and the too-important-to-fail issues are unresolved," the IMF report said.
"The reforms have yet to effect a safer set of financial structures," the report said.
In part, that was due to measures taken by policy makers in some countries and regions to deal with the prolonged crisis that are "delaying a 'reboot' of the system onto a safer path."
The report highlights international reform under way in the banking sector, known as Basel III, which requires a build-up of capital and liquidity buffers to better withstand distress and absorb losses.
Under that reform, to take effect in January 2013, big banks with advantages of scale may be able to better absorb the costs of the regulations, the IMF noted.
"As a result, they may become even more prominent in certain markets, making these markets more concentrated," it said.
Innovative products are being developed to circumvent some new regulations, and banks may be encouraged to move certain activities to the nonbank financial sector, the report warned.
The IMF said the current low interest-rate environment, where the US Federal Reserve and the European Central Bank notably have kept rates slashed, was "crucial" as policy makers try to jump-start economic growth by easing credit.
But it warned that "it may also be creating new vulnerabilities in the future."
Laura Kodres, the IMF's chief of global stability analysis, said at a news conference that the low interest-rate environment means pension funds and insurance companies earn less than they need to be able to meet obligations.
"At some point, they will feel the need to take on riskier activities in order to be able to earn enough" to pay pensioners and policy holders, she said, cautioning that oversight was necessary "to make sure that those things do not get out of hand."
The IMF called for a global-level discussion on certain business activities for banks, after banks' risky investments using their own funds contributed to the financial crisis that swept markets after the Lehman Brothers bankruptcy in September 2008.
The new regulatory agenda "involves making financial institutions less complex and more transparent and lowering the incentives for them to take excessive risk."
The Washington-based global lender also suggested the nonbank or "shadow" financial sector needs better monitoring and regulation to ensure that contagion is limited between banks and nonbanks during a crisis.
"A firm consensus has yet to emerge on what, if any, regulatory action is needed," it said.
IMF managing director Christine Lagarde highlighted Monday the "lasting costs" of a poorly functioning financial sector on global growth.
"Worryingly, the energy to implement the reforms that have been agreed -- as well as the other reforms that we need -- is waning," Lagarde said in a speech in Washington.
"I am often asked, five years into the crisis, whether the financial sector is safer today than it was then. My answer? 'Despite real progress, not yet.'"