The aggregate deficit of U.K. defined benefit occupational pension funds in the Pension Protection Fund's 7800 index increased 5% in May to £118.2 billion ($198.1 billion).
Total liabilities increased 1.8% as of May 31 to £1.289 trillion, while total assets increased 1.4% to £1.171 trillion.
The funding ratio fell to 90.8% from 91.1% at the end of April.
The PPF 7800 index covers 6,150 U.K. pension funds. According to its latest update, 70.7% of the funds were in deficit as May 31, compared with 70.4% at the end of April. The number of funds with a surplus fell to 29.3% from 29.6% at the end of April
The PPF said in its update that the increase in liabilities reflected a fall in nominal and index-linked gilt yields.