The chief executive of $297 billion asset manager Russell Investments said discount brokers' moves to eliminate online commissions could encourage people to make too many trades. "Nothing is necessarily free," Russell CEO Michelle Seitz said in an interview with Business Insider. By and large, asset managers would have reason to be frustrated with discount brokerages cutting visible fees for investors. Costs may then be placed on the managers themselves that use brokers as one of their distribution channels. Visit BI Prime for more stories.