UK - BT Pension Scheme Management has hired Mercer as a strategic partner.
Under the terms of the deal, the consultancy will advise the BT Pension Scheme on manager selection and portfolio implementation.
Specifically, Mercer will be involved in the selection of managers, mandate construction for both equity and fixed income portfolios and the implementation for "certain assets".
The BT Pension Scheme said it would kick off the relationship with a delegated mandate of £480m for European equities and number of other long-term mandates.
The pension scheme, however, will still be responsible for overall decision-making.
Frank Naylor, head of investments for the pension scheme, said he and his colleagues had been impressed by Mercer's ability to "not only advise, but also execute".
Amit Popat, a partner at Mercer, said the deal reinforced his company's view that pension funds - both large and small - were increasingly looking to advisers to help implement investment strategies.
He also pointed out that the two parties had already worked together on allocating more than £4bn in investment mandates over the last two years.