Financial regulators on Sunday issued a series of recommendations to regulate the non-bank or \"shadow\" financial sector, which was estimated to be worth $67 trillion (52.5 trillion euros) in 2011. The sector includes hedge funds and finance companies or securities entities that provide credit or credit guarantees without being regulated like a bank. Following the 2008-2009 financial crisis, in which the collapse of international banks threatened to bring down entire economies, the size and systemic risk of the little-regulated shadow sector has also come under scrutiny. G20 countries in 2011 therefore decided to boost oversight and regulation of the sector, which has grown by between $5 trillion and $6 trillion from 2010 to 2011 and is now equivalent to about half of the banking system\'s assets. On Sunday, international regulatory body the Financial Stability Board (FSB) issued recommendations including imposing minimum standards on methodologies used on certain calculations and carrying out reviews on reporting requirements for fund managers. Pointing out that certain funds may use leverage to boost their returns, the FSB said authorities may also impose limits on the leverage used or require them to maintain sufficient liquid assets as buffers in case their bets go awry. The FSB said it is \"of the view that the authorities\' approach to shadow banking has to be a targeted one\". \"The objective is to ensure that shadow banking is subject to appropriate oversight and regulation to address bank-like risks to financial stability emerging outside the regular banking system while not inhibiting sustainable non-bank financing models that do not pose such risks,\" it said. It added that a \"resilient\" shadow banking sector \"would be welcomed\". The recommendations are open for consultation until January 14, 2013, with final recommendations to be published next September. The US has the world\'s biggest shadow banking system, with assets of $23 trillion in 2011. It is followed by the eurozone with $22 trillion and Britain with $9 trillion. In some economies, the sector is several times the size of the jurisdiction\'s gross domestic product. In Hong Kong the sector is estimated at 520 percent of output, in the Netherlands at 490 percent and Britain at 370 percent.