Finance companies need to review their funding model, says Corporate Affairs Secretary Injeti Srinivas.NEW DELHI: Non-banking housing finance companies are facing liquidity stress, Corporate Affairs Secretary Injeti Srinivas said on Monday.Srinivas said the finance companies need to review their funding model so that they can aim for sustainable growth.A string of defaults at an NBFC, Infrastructure Leasing and Financial Service Ltd (ILFS), have triggered sharp falls in stock and debt markets amid fears of contagion within the rest of the country's financial sector.Shares in housing finance lenders Indiabulls Housing Finance, Dewan Housing Finance Corporation and PNB Housing Finance were trading down between 3 per cent and 8 per cent on Monday.