Massachusetts will propose a rule that would mandate brokers and investment advisers apply a fiduciary standard of care in interactions with clients, Secretary of the Commonwealth William Galvin announced Friday afternoon.

The Massachusetts Securities Division is soliciting preliminary comments on a rule proposal. The comment period will remain open until 5 p.m. on Friday, July 26.

Mr. Galvin said his agency is proposing a fiduciary standard of care in response to the Securities and Exchange Commission’s Regulation Best Interest, the final iteration of which was issued June 5, which he believes didn’t go far enough to rein in broker conduct.

“We are proposing this standard, because the SEC has failed to provide investors with the protections they need against conflicts of interest in the financial industry, with its recent ‘Regulation Best Interest’ rule,” Mr. Galvin said.

The fiduciary obligation will apply to recommendations, advice and to the selection of account types, according to the announcement. Therefore, it will apply to individual retirement account rollovers, as well as recommendations to open accounts involving asset-based or transaction-based remuneration, it said.

“My office has seen firsthand the serious financial harm that investors and savers have suffered as a result of conflicted financial advice,” he said. “Investors must come first.”

Massachusetts joins New Jersey and Nevada, which are also pursuing fiduciary rules in their respective states. Maryland lawmakers have tabled a similar bill in their state for now.

Some states have felt compelled to address broker and adviser conduct after a Department of Labor fiduciary regulation was killed in the Fifth Circuit Court of Appeals in March 2018. That rule, an Obama-era regulation that took partial effect in June 2017, would have raised investment advice standards in retirement accounts such as IRAs and 401(k)s.

The brokerage industry had argued against the DOL rule partly because it said the SEC, as the federal securities regulator, should be the body to rewrite investment-advice rules. Mr. Galvin and investor advocates feel the SEC’s investment-advice rule didn’t go far enough, while the brokerage industry has said it raises the bar from the existing “suitability” standard.