Terminology

Before exploring who facilitates trades and what they cost, you need the vocabulary of the trading floor: the quotes, orders, accounts, and transaction types that make securities trading work.


Bid, Ask, and Spread

When a security is available for trading, two prices are always quoted:

  • Bid: The highest price a buyer is willing to pay for a security
  • Ask (Offer): The lowest price a seller is willing to accept for a security
  • Quote: The current bid and ask prices displayed together (e.g., "50.00 bid / 50.25 ask")

The bid-ask spread is the difference between the bid and ask prices. It represents an implicit transaction cost; the wider the spread, the more expensive it is to trade.

  • Narrow spread = high liquidity (many buyers and sellers, actively traded)
  • Wide spread = low liquidity (fewer participants, thinly traded)

Exam Tip: Gotchas

The bid-ask spread is a cost to the investor even though no one sends you a bill for it. If you buy at the ask and immediately sell at the bid, you lose the spread. The exam may test whether you recognize the spread as a trading cost.


Order Types

How you enter an order determines what you prioritize: guaranteed execution or guaranteed price. You cannot have both.

Order TypeGuaranteesDoes NOT GuaranteeBecomes
MarketExecutionPriceN/A (executes immediately)
LimitPrice (or better)ExecutionN/A (stays as limit)
StopN/A (triggers action)Price or executionMarket order when triggered
Stop-limitN/A (triggers action)ExecutionLimit order when triggered

Market Orders

  • Executed immediately at the best available price
  • Guarantees execution but not price
  • Best for liquid securities where price is relatively stable
  • Risk: In fast-moving markets, the execution price may differ significantly from the last quoted price (slippage)

Limit Orders

  • Executed only at the specified price or better
  • Guarantees price but not execution (the order may never fill if the market doesn't reach your price)
  • Buy limit: Set below the current market price (you want to buy cheaper)
  • Sell limit: Set above the current market price (you want to sell higher)

Stop Orders (Stop-Loss Orders)

  • A stop order becomes a market order when the stop price is reached
  • Used to limit losses or protect profits
  • Sell stop: Set below current market price; triggers a sale if the price drops to the stop level (protects a long position)
  • Buy stop: Set above current market price; triggers a purchase if the price rises to the stop level (protects a short position or enters on a breakout)

Stop-Limit Orders

  • A stop-limit order becomes a limit order (not a market order) when the stop price is reached
  • Combines features of both stop and limit orders
  • Provides more price control than a stop order, but execution is not guaranteed (the limit price may never be reached after triggering)

Exam Tip: Gotchas

A stop order becomes a market order when triggered. A stop-limit order becomes a limit order when triggered. The exam frequently tests this distinction. Remember: stop = market (execution likely), stop-limit = limit (price protected but may not fill).

Quick Reference: Where to Place Orders

OrderPlacementPurpose
Buy limitBelow marketBuy at a lower price
Sell limitAbove marketSell at a higher price
Sell stopBelow marketLimit losses / protect profits on a long position
Buy stopAbove marketLimit losses on a short position / enter on breakout

Account Types

The type of account determines how trades are funded and what strategies are permitted.

Cash Accounts

  • Securities must be paid in full at the time of purchase
  • No borrowing from the broker-dealer
  • No short selling - you must own the security before you can sell it

Margin Accounts

  • The investor can borrow from the broker-dealer to purchase securities (buying on margin)
  • Borrowing amplifies both gains and losses (leverage)

Key margin rules:

RuleSet ByRequirement
Regulation T (initial margin)Federal Reserve BoardInvestor must deposit at least 50% of the purchase price
Maintenance marginFINRAInvestor must maintain at least 25% equity at all times
  • Margin call: Issued when the investor's equity falls below the maintenance level
  • The investor must respond by depositing additional funds or securities
  • If the investor fails to meet the margin call, the broker-dealer can liquidate positions without the investor's consent

Exam Tip: Gotchas

Regulation T is set by the Federal Reserve (50% initial). Maintenance margin is set by FINRA (25% minimum). The exam tests who sets each requirement. Remember: the Fed sets the entry bar, FINRA sets the ongoing floor.

Short Sales

  • Short selling means selling securities the investor does not own (borrowed from the broker-dealer)
  • The investor profits if the price declines (buy back cheaper)
  • Unlimited risk if the price rises (there is no ceiling on how high a stock can go)
  • Requires a margin account - short selling is not permitted in cash accounts
  • Subject to Regulation SHO (SEC rule requiring brokers to locate shares before executing a short sale)

Transaction Types

How a broker-dealer is compensated depends on the role it plays in the transaction.

RoleActing AsCompensationTrades From
Principal (dealer)DealerMarkup (on sale) or markdown (on purchase)Own inventory
Agent (broker)BrokerCommissionCustomer's order

Principal (Dealer) Transactions

  • The broker-dealer trades from its own inventory
  • On a sale to a customer, it charges a markup (price above the market)
  • On a purchase from a customer, it charges a markdown (price below the market)

Agency (Broker) Transactions

  • The broker-dealer executes the trade on behalf of the customer in the open market
  • Charges a commission for the service

Payment for Order Flow

  • Payment for order flow (PFOF) is compensation received by a broker-dealer from a market maker for routing customer orders to that market maker
  • The market maker profits from the spread on the routed orders and shares a portion with the routing broker
  • PFOF must be disclosed to customers (SEC Rule 607)
  • Raises a potential conflict of interest: the broker may route orders to the market maker that pays the highest rebate rather than the one that provides the best execution

Exam Tip: Gotchas

A firm cannot charge both a commission and a markup on the same transaction. If it acts as principal, it charges a markup/markdown. If it acts as agent, it charges a commission. The exam tests whether you can identify the transaction type based on the compensation described.