FTSE350 firms are finding it harder to fulfil their defined benefit (DB) pension obligations now than at any point since 2009, according to research by PwC.
The UK's biggest companies were given a score of 69 out of 100 for their relationship between financial strength and the size of their DB pension scheme commitments.
This is down from 82 in 2015, with a fall in long-term guilt yields resulting in increased company deficits, and The Pensions Regulator estimating that 5% of schemes are now at risk, or already failing to, meet obligations.
"This score is the largest drop since the recession," PwC pension credit advisory practice head, Jonathon Land, said.
"The last time we saw a fall this big was because of company performance, this time it's because of scheme size.
"If a combination of political uncertainty following the election and Brexit leads to another economic jolt to company performance, this would be a double-whammy for pension scheme support."
PwC's Pensions Support Index shows FTSE350 companies' ability to meet DB pension obligations since 2006:
The PwC analysis shows schemes that struggle to meet their commitments, and have significant outgoings to cover member benefits, risk becoming cash flow negative and forced to sell assets to pay liabilities.
"For many, with either a weak covenant or a relatively mature scheme, time is running out," Land continued.
"These schemes need to focus on the strength of their employer, the ability to make increased contributions, and the risks attached to their investment strategy."
This comes after research by Mercer earlier this month showed that 55% of UK DB schemes are cash flow negative, up from 42% last year, with 85% of those remaining also set to be cash flow negative by 2027.
"Being cash flow negative is a natural life stage of a mature DB pension scheme, of course, but recent stock market performance may have lulled some into a false sense of security," Mercer global director of strategic research, Phil Edwards, said.
"Trustees of cash flow negative schemes need to be sure that, in the event of a large market correction, liquid assets are available to meet cash flow and collateral needs, without requiring the scheme to crystallise losses."
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