The managed accounts platform that Boston-based Fidelity Investments offers for workplace retirement accounts last year added 784 new plan sponsors, representing an additional 740,000 eligible workers.

The number of new retirement plan sponsors using the Portfolio Advisory Service at Work (PAS-W) jumped 78 percent compared with those who signed up in 2012, Fidelity said.

Fidelity also reported enrolled participants in PAS-W grew by 51 percent in 2013 to 94,500, and assets under management grew by 54 percent to $7.3 billion.

New clients represent organizations of various sizes across a wide variety of industries, including technology, manufacturing, telecommunications, higher education, health care and others, according to Fidelity.

Investment managers on the platform actively manage accounts in an attempt to balance growth and control risk based on a retirement plan participant's financial situation and risk tolerance.

“For many American workers, their retirements savings is going to be the biggest investment in their life – more than they’ll invest in a house, a college education for their children, or any other investment,” said Sangeeta Moorjani, senior vice president of Fidelity’s Professional Services Group. “As a result, an increasing number of workers are turning to Fidelity PAS-W to help them tailor a retirement plan that meets their specific investment needs as well as adjusts to their level of risk and changing financial circumstances.”