If your broker recommended a series of trades in your retirement portfolio or your account has shown high turnover and heavy commissions, what FINRA found about Mack Leon Miller may be worth knowing. According to FINRA records, Miller (CRD# 2822317), was suspended from all securities activities as of September 2, 2025, for what the regulator found to be excessive and unsuitable trading that harmed senior investors.
The record contains two regulatory disciplinary actions spanning 2020 and 2025, both resolved through Acceptance, Waiver and Consent letters (AWCs).
Excessive trading that cost senior customers $71,022 in realized losses
According to FINRA’s October 2025 disciplinary actions report, an Acceptance, Waiver and Consent (AWC) was issued on August 11, 2025, in which Miller was suspended from association with any FINRA member in all capacities for nine months. In light of Miller’s financial status, no monetary sanctions were imposed.
Without admitting or denying the findings, Miller consented to the sanctions and to the entry of findings that he willfully violated Regulation Best Interest under Rule 15l-1(a)(1) of the Securities Exchange Act of 1934 (Reg BI) when he recommended a series of trades that were excessive, unsuitable, and not in two senior customers’ best interests. According to FINRA’s record, Miller’s trading generated $32,230 in commissions and resulted in $71,022 in realized losses for the customers.
According to the AWC, one of the customers relied on Miller’s advice and routinely followed his recommendations, and as a result, Miller exercised de facto control over that customer’s account. The AWC shows that the suspension is in effect from September 2, 2025, through June 1, 2026.
An earlier regulatory action involving unsuitable trading in a senior’s account
Before the 2025 suspension, FINRA also disciplined Miller in 2020 for similar conduct. According to FINRA records, an AWC was issued on April 9, 2020, in case #2018057302701, in which Miller was suspended from association with any FINRA member in all capacities for five months and ordered to pay restitution of $2,500, plus interest (though partial restitution was imposed due to Miller’s financial status).
In that action, without admitting or denying the findings, Miller consented to the sanctions and to the entry of findings that he engaged in unsuitable trading in the account of a customer who was over 79 years old and retired. According to FINRA’s findings, Miller actively traded the customer’s account, resulting in a high turnover rate and cost-to-equity ratio, as well as significant losses. The findings stated that Miller typically purchased and held different stocks for short periods, including for under one week. The costs of the trading strategy, in the form of mounting commissions and fees, made it difficult for the customer to profit from the trades. Miller then recommended even more active trading in the customer’s account.
According to the AWC, as a result of Miller’s trading, the customer lost $69,633. The suspension was in effect for 5 months.
Churning and excessive trading: how this misconduct harms investors
Excessive trading, also known as churning, occurs when a broker trades excessively in a customer’s account to generate commissions, without regard for the customer’s best interest. The hallmark of churning is trading volume that is inconsistent with the customer’s investment objectives and financial situation.
In Miller’s cases, FINRA found that the trading frequency, turnover rate, and cost-to-equity ratio were all inconsistent with customers who were retired or near retirement age. For customers in this demographic, capital preservation and income generation are typically the investment goals, not frequent trading of individual securities.
The financial harm is compounded by two mechanisms: (1) commissions and fees paid on every transaction erode account value, and (2) frequent trading accelerates the time at which losses accumulate. When a broker holds a security for days or weeks before selling it, the customer faces the full impact of any price decline, multiplied across dozens of transactions. Over time, the cumulative effect makes it mathematically impossible for the customer to break even or profit.
Legal framework: Regulation Best Interest, FINRA Rules 2111 and 2010
Excessive trading in customers’ accounts violates several core securities regulations:
Regulation Best Interest (Reg BI): For recommendations made on or after June 30, 2020, brokers must act in customers’ best interest when recommending securities. Reg BI prohibits recommending trades that are excessive relative to the customer’s investment objectives, financial situation, and needs. FINRA found that Miller willfully violated Reg BI by recommending excessive and unsuitable trades to his senior customers.
FINRA Rule 2111 (suitability): For recommendations made before June 30, 2020, brokers must have a reasonable basis for recommending a security or strategy, must ensure the recommendation is suitable for the customer’s investment profile, and must ensure the recommendation does not involve excessive trading. FINRA found that Miller’s 2020 trading violated Rule 2111 as well.
FINRA Rule 2010 (conduct standards): Brokers must observe high standards of commercial honor and just and equitable principles of trade. Excessive trading that generates commissions for the broker while harming the customer’s account violates FINRA Rule 2010.
What investors should know
If you invested with a broker who made frequent trades in your account without your explicit approval or request, the trading frequency may have been excessive. Red flags for excessive trading include:
- High turnover in your account (many securities bought and sold each month)
- High commissions and fees relative to your account value
- Recommendations to trade short-term when your investment objective is long-term capital preservation
- Holding periods of days or weeks for individual securities (inconsistent with retirement investing)
- Losses that accumulate despite a rising overall market
If any of these patterns apply to your account, a free consultation with a securities law attorney can help you understand whether you have a potential claim for damages.
Steps to take right now
- Gather your account statements, trade confirmations, and any correspondence with your broker or firm, including emails, texts, and written materials about the investments.
- Look up your broker on FINRA BrokerCheck at brokercheck.finra.org to review their full disclosure record.
- Contact a securities arbitration attorney for a consultation to evaluate your options.
Rosenberger + Kawabata represents retail investors in FINRA arbitration proceedings involving excessive and unsuitable trading, including cases against brokers at Spartan Capital Securities and other firms. If you traded with Mack Leon Miller and experienced losses due to excessive or unsuitable recommendations, contact Rosenberger + Kawabata online for a free and confidential consultation, or call (310) 894-6921.
The information in this post comes from FINRA’s public BrokerCheck database. You can view the full detailed report (CRD# 2822317) here.
You can view the full October 2025 FINRA disciplinary actions report here.