When you go to the doctor, there’s an expectation that she will act in your best interest. You don’t expect to be prescribed costly pills because the office is getting a commission from the drug company, when a healthier diet will do the trick.

The next time you get a financial checkup or make an investment, there will be new rules about what you can expect from your investment professional. But the rules shouldn’t necessarily give investors the comfort of a doctor-patient relationship.

The changes made by the Securities and Exchange Commission on Wednesday are voluminous — one rule change alone takes up 771 pages — but the agency said they would help ensure investors get advice they can count on.

Not everyone is convinced. Consumer advocates say the changes have weakened the standards governing one class of financial professionals while giving an unwarranted veneer of trustworthiness to another.