Massachusetts' securities regulator on Wednesday charged Fidelity Brokerage Services with improperly "rubber-stamping" applications to trade options, saying the "blatantly unethical" practice allowed some ineligible retail investors to trade in meme stocks.

Secretary of State William Galvin said Fidelity, with 30.9 million retail brokerage accounts and $11.1 trillion of assets under management as of Sept. 30, betrayed a "half-hearted and lackadaisical attitude" toward investor protection when vetting applications for options and margins trading.

The administrative complaint against Fidelity came as regulators try to ensure that ordinary investors understand the risks of trading in options and other complex products, as smartphone apps make it easier to dive into securities markets.

Fidelity said it has cooperated fully with Galvin's office, but disagreed with how the complaint characterized the company.

"We have effective due diligence processes, and look forward to addressing and resolving this matter through the administrative process," Fidelity said in a statement.

Galvin said Fidelity's systems let investors submit multiple options trading applications containing ever-inflating claims, and failed to spot bogus claims of employment status, investing experience and financial wealth.

He said one investor submitted 11 applications in one week, including a sudden change in job title from "Scientist" to "CEO," and upon winning approval traded options in meme stocks including AMC Entertainment, BlackBerry and Nokia.

Given the popularity of mobile apps and of options trading among young investors, "broker-dealers need to make sure they're still maintaining the same standard of care and attention and making sure these investors qualify," Galvin said.

Massachusetts wants Fidelity to pay a civil fine, hire an independent compliance consultant and avoid future violations.

Options give investors the right but not the obligation to buy and sell stocks. Margin trading lets investors trade stocks with borrowed money. Both can result in higher or lower returns, and more risk, than from ordinary stock trading.

Last June, Robinhood agreed to pay $69.6 million in fines and restitution to settle a variety of claims by the Financial Industry Regulatory Authority, including that it approved thousands of ineligible customers to trade options. The company went public as Robinhood Markets Inc. one month later.