As we all know, fees impact net returns. For mutual funds, aside from any load, the two primary fees charged are management fees and 12b-1 fees. The management fees are easy to understand. The 12b-1 fees, however, are not. They are designed to cover distribution costs, but this is a broad term. In reality, much of this fee is used to pay brokers/advisors for directing client business to the funds. As a recent article (Investment News) suggests, the SEC may begin to limit such payouts.
Dolvin, Steven D., "Mutual Fund Fees" (2016). All Chapters. 149.