About 200 shopping centres with a nominal value of £7B have upcoming debt maturity issues that are piling pressure on their owners, according to research from asset management firm APAM.

The firm monitors shopping centres bought using debt in the U.K. It said that around 200 centres bought between 2012 and 2015 are now coming to the end of their financing periods and will find it difficult to refinance existing loans, according to Property Week. Many will breach debt covenants and could face administration if the income they produce is not enough to cover interest payments.

There is £25B of debt secured against U.K. retail assets, a figure that has fallen by around £3B a year since 2007 as lenders pull back from the sector, according to the Cass Commercial Real Estate Lending Report.

APAM said the value of centres facing debt pressure has risen from £4B in the past year, because of the high number of retail CVAs and administrations and the fall in values in the sector.

Many of these centres are owned by private equity firms that bought them from banks or other distressed owners at what they thought were cheap prices, but with refinancing tough and few buyers for these assets, the hunters have become the hunted.

As first reported by Bisnow, one of the starkest examples of falling values in the sector is Callendar Square in Falkirk. Bought for £25M in 2006, it sold at auction last year for just £1M.

“[Private equity owners] have sat on the income and haven’t been reinvesting,” APAM Executive Director Simon Cooke said. He added that the ownership structure of centres was as big a factor in their failure as any inherent weakness in physical retail.

Local councils have been significant buyers of town centre retail schemes and shopping centres, with firms like APAM, Ellandi and NewRiver gearing up to provide the property expertise needed to help revive struggling schemes, and convert defunct retail space to other uses like residential or community facilities like libraries.