The exchange traded fund industry has cultivated a strong following in the marketplace, but it has not made much headway into mutual fund dominated 401(k) plans. However, more retirement investment firms are beginning to make the shift as the market becomes more transparent.

ExpertPlan recently announced that it will add more than 900 ETFs, including those offered by Barclays, Claymore, First Trust, iShares, Rydex and Wisdomtree, to its retirement plan platform, with Matrix Financial Solutions providing custody, trading and clearing services, reports Mariana Lemann for Ignites. [ETFs: Coming to a 401(k) Plan Near You]

ETFs, which have over $1 trillion in assets under management, have not made a major dent in the 401(k) industry. According to Cerulli Associates, ETF assets in 401(k) plans account for $5 billion, or 0.2% of total assets in 2010, whereas mutual funds made up $1.8 trillion, or 58% of 401(k) assets.

ExpertPlan is making its move ahead of the new Department of Labor’s fiduciary and 408(b)(2) fee disclosure rules, Ignites reports. The firm joins other notable ETF 401(k) plan providers like ShareBuilder, Schwab, TD Ameritrade and Invest’n’Retire. [Growing Demand For ETF-Based 401(k)s]

“Over the years we have increased our business significantly by partnering with fee-based financial advisors who are looking for the most efficient investment vehicle both with regards to performance and cost,” Ross Brown, senior VP of sales and relationship management for ExpertPlan, said in the Ignites article. “ETFs were a natural addition to our lineup in order to meet that demand.”