The ICI Pension Fund has insured a further £1.8bn (€2.4bn) of its liabilities, following a 2014 buy-in worth £3.6bn.

Combined with the 2014 deal that saw a £3bn buy-in agreed with Legal & General (L&G) and a £600m agreement struck with Prudentialto date the largest buy-ins conducted in the UK – the £9.5bn fund for workers of Imperial Chemical Industries has now insured more than half its liabilities.

The £1.8bn insured since the initial deal was announced were transferred to L&G and Prudential in four separate transactions – bringing the number of transactions agreed with each insurer to three, according to a letter sent to the fund’s members earlier this year.

Consultancy LCP said scheme trustees had agreed the transfer as part of a so-called umbrella contract, likening the approach to one taken when using swaps and derivatives.

Clive Wellsteed – who, as head of LCP’s de-risking practice, led on the transactions – said: “The key advantage of the ‘umbrella and schedule’ approach is that the trustee can move quickly to insure additional tranches of liabilities when competitive pricing becomes available, as the execution process is limited to documentation of the key ‘tranche-specific’ parameters.”

Wellsteed said the parameters that needed to be agreed included how the policy’s premium would be paid, and the timescale for the cleansing of any scheme membership data.

Heath Mottram, chief executive of the scheme, said he had no doubt the approach pursued by the fund had improved the pricing achieved.

According to the fund’s latest funding statement, its coverage ratio stood at 93% in March, a marginal improvement of 2 percentage points over 2014.

However, in a letter to members explaining the additional bulk annuity deals agreed since 2014, the chairman of the fund, David Gee, credited the improvement to a deficit-reduction payment made by sponsor AkzoNobel in January.

The letter added that a revised deficit-reduction plan would see the Dutch parent company pay £978m into the fund by 2021.

The UK has to date been the single-largest market for de-risking transactions, such as ICI’s acquisition of bulk annuities.

According to a paper by Prudential, the transactions across the UK, Canada and the US were worth $260bn (€231bn) between 2007 and the end of June – with the UK accounting for nearly 70% of deals, and the US one-quarter.

The insurer said 40 pension funds had completed deals worth $1bn or more during the period.