If you opened a brokerage statement and saw trades you never approved, the experience can feel surreal. Many investors assume there must be a clerical mistake, a misunderstanding, or some kind of harmless timing issue. In some cases, that may be true. In others, the activity raises a much more serious question: was this unauthorized trading?
In general terms, unauthorized trading refers to transactions placed in an account without the customer’s permission, unless the broker had properly documented discretionary authority. FINRA Rule 3260 states that a registered representative generally cannot exercise discretionary power in a customer account without the customer’s prior written authorization and the firm’s written acceptance of that arrangement (FINRA Rule 3260). FINRA’s discovery rules for customer cases also specifically recognize unauthorized trading as a distinct type of claim and identify the documents both sides are expected to produce in that kind of dispute (FINRA Discovery Guide, PDF).
For beginners, that legal framework can sound technical fast. This post breaks it down in plain English. In this post you’ll learn what unauthorized trading is, how it differs from permitted discretion, what evidence often matters, how FINRA arbitration works, and why many investors explore legal help early when trades appear in an account without approval. If you want a broader overview before diving into the arbitration side, this related guide on what unauthorized trading claims usually involve may help set the stage.
<aside> 💡 Scroll to the bottom for every post in this series.
</aside>
At its core, unauthorized trading is usually about consent.
A broker may enter a trade when the customer has approved the transaction, or when the account has been set up as a discretionary account with the required written authority. Without that, placing trades on the customer’s behalf can become a regulatory and legal issue. FINRA Rule 3260 is especially important here because it says discretionary trading authority generally requires both written customer authorization and written firm approval (FINRA Rule 3260).
The same rule also contains a narrow exception for time-and-price discretion. If a customer gave an order for a definite amount of a specific security, the broker may sometimes have limited discretion over the exact time or price of execution. But FINRA says that authority generally lasts only until the end of the same business day unless there is a specific written indication to the contrary signed and dated by the customer (FINRA Rule 3260).
That distinction matters. A broker may not turn a one-day instruction about timing into broad permission to buy and sell whenever they want.
This is where many beginners get tripped up.
Some investors intentionally give a broker discretion to trade without checking in before each order. That type of relationship can be lawful, but FINRA’s rules still require the proper paperwork and supervisory approval. Under Rule 3260, the customer’s written authorization alone is not the entire story; the member firm also has to accept the account in writing, and discretionary orders are subject to approval and review (FINRA Rule 3260).
FINRA also requires firms to maintain supervisory systems designed to achieve compliance with securities laws and FINRA rules, which often becomes relevant when investors allege that unauthorized trades were not caught internally (FINRA Rule 3110).
So, if a broker says, “You trusted me to handle things,” that does not automatically answer the legal question. In many disputes, the real issue is whether the account was properly authorized as discretionary and whether the firm’s records actually support the broker’s version.
Unauthorized trading claims can arise in several different ways:
This is the classic example. The investor never approved the order, but the transaction appears on the confirmation and statement anyway.