Fidelity Investments says it has had good success with its Advisor 401(k) business in 2009; these plans are offered through third-party financial advisors to small and mid-sized companies.

According to the ICI, nearly three-quarters of 401(k) plans under $50 million are sold through an advisor, up from 52 percent in 2003.

Fidelity’s Advisor 401(k) platform sold 533 plans last year, bringing the total number of advisor-sold 401(k) plans administered to a record 3,655. Assets in these plans grew more than 30 percent to $23.2 billion.

Some 1,315 plans were utilizing auto enrollment, up 33 percent from 2008. And the number of plans offering auto annual increase grew 34 percent in 2009 over 2008.