The aggregate deficit of all U.K. corporate pension funds increased 70% to £289 billion ($434.1 billion) for the year ended Jan. 31, said JLT Employee Benefits.
JLT's monthly index showed that, despite a 13.2% increase in assets over the year to £1.27 trillion, liabilities grew more, by 20.7% to £1.56 trillion.
Deficits also increased 16.1% in January. Assets increased 3.7% and liabilities jumped 5.8% for the month.
The funding level of those pension funds consequently decreased to 82% from 87% as of Jan. 31, 2014.
FTSE 100 companies saw their pension deficits increase 58% on aggregate to £98 billion, while FTSE 350 company pension deficits increased 57.7% to £112 billion. Funding levels for both the largest 100 and largest 350 U.K. companies each decreased four percentage points to 85% for the 12-month period.
Charles Cowling, director at JLT Employee Benefits, attributed the increased liabilities to a continued fall in bond yields, he said in a statement accompanying the index. He also said it is possible for interest rates to fall even lower, leading to higher pension fund liabilities.