Fiduciary

A fiduciary is legally required to act in a client's best interest, ahead of their own financial interest, when giving advice or managing money. Registered investment advisors are generally held to a fiduciary standard; many brokers historically operated under a lower "suitability" standard, which only required recommendations to be appropriate, not necessarily optimal.

The distinction matters most around fees and product recommendations: a fiduciary who steers a client toward a higher-cost fund that pays the advisor a bigger commission, when a cheaper equivalent exists, is violating their duty in a way a suitability-only advisor technically might not be.