The Rentokil Initial 2015 Pension Scheme has secured a buy-in covering 14,200 members in a £1.5bn deal with Pension Insurance Corporation (PIC).
The transaction means the scheme is now fully hedged against longevity, interest rate and inflation risks - bringing it closer to full buyout, which is anticipated in 2020.
The buy-in is also PIC's largest for 2018 and represents a quarter of its announced bulk annuity volumes this year, which now total £6bn.
The scheme was 100.8% funded at its most recent triennial valuation, dated 31 December 2015, and its membership comprises 7,500 pensioners and 6,700 deferred pensioners.
Trustee chairman Chris Pearce said the deal was "great news for members".
"After many years of support from Rentokil Initial and careful management with Aon (our actuary) and Willis Towers Watson (our investment adviser), we can now secure our members' benefits through PIC, a company which has strong financial credentials and a track record of excellent customer service."
PIC head of business development Mitul Magudia added: "We are proud to have secured this buy-in, which will guarantee the benefits of the 14,200 members of the pension scheme. This is PIC's largest transaction in 2018 and will be one of the largest full buyouts ever undertaken in the UK."
Rentokil Initial chief executive Andy Ransom said company funding of the scheme, as well as "excellent stewardship" by scheme trustees, had resulted in the "very positive situation".
Aon partner John Baines, who advised the scheme, also welcomed the deal, noting "attractive pricing" had been captured during the busy year despite being "surrounded by other large transactions in the market".
"The deal was made possible by reacting quickly to wider market developments in order to bring together an attractively-priced, innovative and bespoke agreement."
The deal brings total announced bulk annuity volumes, in an already record-breaking year, to £18.6bn, far in excess of the previous record year, 2014, when deals amounted to £13.2bn.
In July, the Rentokil Initial Pension Trustee company was fined £25,000 by The Pensions Regulator for failing to complete two valuations for another of the company's schemes, the Initial Hospital Service No.1 Pension Scheme.
Aviva Life & Pensions has concluded an £875m buy-in with its own staff pension scheme, following on from a similar transaction last year.
Just Group has completed a £74m pensioner buy-in with the UK pension scheme of a US-listed engineering business.
The Smiths Industries Pension Scheme has secured a £146m buy-in with Canada Life in its fourth bulk annuity and its sponsor’s tenth overall.
The Prudential Staff Pension Scheme has entered into a £3.7bn longevity swap with Pacific Life Re, insuring the longevity risk of over 20,000 pensioners.
The Baker Hughes (UK) Pension Plan has secured approximately £100m of liabilities through a buy-in with Just Group.