Assets in the Fidelity Advisor 401(k) platform leaped 26% in 2007, to $21.1 billion. The number of new plans that were funded jumped 21%, to a record-high of 516 plans. All told, the 401(k) program had 2,825 plans at year-end, an increase of 15% over 2006.

   The Fidelity Advisor 401(k) platform is sold exclusively through third-party financial advisors to small- and mid-sized companies.    Fidelity offers 401(k) plans through three channels: its direct business, where companies deal directly with Fidelity; through financial advisors via Fidelity Investments Institutional Services; and through third-party administrators. A spokesman said that Fidelity is investing heavily to increase its market share in the advisor-sold space.