National Employment Savings Trust, London, boosted its assets 111% to £5.7 billion ($7.4 billion) for the 12 months ended March 31.
The U.K. government-backed multiemployer defined contribution plan, known as a master trust, is also now managing assets on behalf of 7.9 million participants and 720,000 employers up from 6.4 million and 616,000, respectively, a year earlier.
NEST delivered an average annualized return of 9.2% net of fees over the five years ended March 31 for funds in the growth phase of the default strategy and 7.8% for the 12-month period.
NEST's investments in equities increased £2.9 billion as of March 31 from £1.4 billion a year earlier.
Bond investments were boosted to £1.9 billion from £873 million; property investments increased to £425 million from £262 million; while cash increased to £362 million from £147 million.
"We are making good progress with the future procurement of scheme administration services," said Otto Thoresen, NEST Corp. chairman, in a news release. "The aim is to make the scheme ready for a digital world, improving our service and also harnessing advances in technology to further increase efficiency."