Fidelity Investments expects sales of its 401(k)’s to continue to increase through third-party financial advisors to small and midsized companies – and the company plans to reduce fees to gain additional share.

In August, Fidelity plans to switch its Advisor 401(k) platform to a system where the advisor receives a flat fee from Fidelity instead of several different fees in the form of 12b-1 fees.

Analysts said that Fidelity is trying to keep pace as other broker-dealers are flattening their fee structure.

Last year, Fidelity’s Advisor 401(k) program platform sold 533 plans, bringing its total number of advisor-sold 401(k) plans under administration to 3,655. This increased advisor-sold 401(k) assets under administration 30% to $23.2 billion as the Boston-based company increased its participant base 8% to 640,000.

The business has grown at an annual rate of 15% over the past years, according to Rich Linton, the head of Fidelity Advisor 401(k) and an executive vice president of retirement for Fidelity Investments Institutional Services.

He said the unit continues to see strong growth this year as more small and mid-sized businesses continue to turn to advisors as they establish retirement plans.

“We expect continued growth in this space over the next three years,” Linton said. “Our success combined with the success of advisors will lead a lot of assets our way.”

According to 401kExchange, nearly three-quarters of 401(k) plans under $50 million are sold through advisors, up from 52% in 2003.

Fidelity will face stiff competition from other providers, including Vanguard and Charles Schwab, that offer retirement products and services to advisors.

Linton said Fidelity has a “healthy respect for all of the competition in the market,” but he thinks Fidelity has an opportunity to gather additional share.

“Honestly for us, it is just a matter of getting out and telling our story with as many advisors as we can,” he said. “We can help advisors as they grow their practice. We can provide tools for them to be successful in serving plan sponsors. We want to become the platform of choice for advisors and plan sponsors.”

Many of Fidelity’s services were being used by plan sponsors. As of Dec. 31, 1,315 Fidelity Advisor 401(k) were using auto enrollment, up 33% from a year earlier.