A market order instructs your broker to buy or sell immediately at the best available current price. You get filled straight away, but you have no control over the exact price you receive.
Priority of a market order: Speed over price. You will always get filled. You will not always get the price you saw on your screen when you clicked.
How market orders work
1
You click Buy Market on Apple stock showing a price of $195.50
2
Your broker routes the order to the exchange instantly
3
The order matches against the lowest available ask price on the order book
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You are filled. The actual price may be $195.52, $195.55, or more depending on market conditions
Filled
When to use market orders
Good situations
Highly liquid stocks with tight spreads (SPY, AAPL, TSLA). Urgent exits on a fast-moving position. Small share quantities where slippage impact is minimal.
Avoid when
Trading options with wide spreads. Trading low-volume, thinly traded stocks. Pre-market or after-hours sessions when liquidity is thin and prices can jump wildly.
Slippage: The difference between the price you saw and the price you got. On a liquid stock, slippage might be $0.01. On a thinly traded option or stock, it could be $0.50 or more per share. Always factor slippage into your cost calculations.
Execution speed
Instant
Fills immediately at current market price
Price certainty
None
You accept whatever price the market gives you
Fill guarantee
Yes
Your order will be filled as long as markets are open
Best for
Liquid assets
Stocks and ETFs with high daily volume
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Order Types
Limit orders
A limit order lets you specify the exact price at which you are willing to buy or sell. The order only executes at your specified price or better. You control the price but sacrifice the guarantee of execution.
Priority of a limit order: Price over speed. You set the price you want. The order waits until the market reaches your price. It may never fill if the price moves away.
Buying with a limit order
Example: Buying Apple at $194.00
AAPL is trading at $195.50. You place a buy limit order at $194.00. Your order sits on the order book waiting. If AAPL dips to $194.00 or below, you get filled at $194.00 or better. If AAPL never reaches $194.00, the order expires unfilled.
Selling with a limit order
Example: Selling Apple at $200.00
You own AAPL at $195.50. You place a sell limit order at $200.00. The order waits. When AAPL reaches $200.00, your shares are sold at $200.00 or better. If AAPL never reaches $200.00, you remain long.
Limit orders for options
Always use limit orders when trading options. The bid-ask spread on options can be $0.20, $0.50, or even $2.00 wide. A market order on options fills at the ask (worst price for buyers) or bid (worst price for sellers). A limit order at the midpoint typically gets a fair fill.
Advantages
Control your exact entry and exit price. Avoid slippage. Protect against unfavorable fills on wide-spread options. Set and forget.
Disadvantages
May not fill if price never reaches your level. Can miss fast-moving opportunities. Requires monitoring or order management.
GTCGood Till Cancelled. The order stays active until filled or you cancel it manually. Can remain open for days or weeks.
Day orderAutomatically cancels at the end of the trading day if unfilled. The most common default setting.
IOCImmediate Or Cancel. Fill whatever quantity is available right now at your price, cancel the rest. Used for large orders.
FOKFill Or Kill. Fill the entire order immediately at your price or cancel the whole thing. No partial fills allowed.
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Order Types
Other order types
Beyond market and limit orders, brokers offer several other order types that combine price control with conditional triggers. These are especially useful for automating risk management.
SL
Stop loss order (stop order)
Sits dormant until the stock hits your trigger price, then executes as a market order. Used to limit downside. If you own AAPL at $195 and set a stop at $185, a sell stop triggers automatically if AAPL drops to $185, exiting the position.
SL
Stop limit order
Like a stop order but converts to a limit order (not market) when triggered. Gives you price control after the trigger but risks not filling if the stock gaps past your limit. Trigger: $185. Limit: $184.50. Only fills at $184.50 or better.
TS
Trailing stop order
A stop loss that moves with the price automatically. Set a trailing stop of $5 on AAPL at $195 and your stop is $190. If AAPL rises to $210, your stop moves up to $205. Locks in profit as the stock climbs while still protecting against reversal.
OCO
One Cancels Other (OCO)
Links two orders together. When one fills, the other is automatically cancelled. Commonly used to set both a take profit limit and a stop loss simultaneously. As soon as one triggers, the other disappears.
MOO
Market on Open / Market on Close
Executes at the market opening price (MOO) or closing price (MOC). Used by institutional traders to participate in the opening or closing auction at the day's official price.
For options traders: The most important order types to master are the limit order (for all entries and exits) and the OCO order (to set your stop loss and take profit simultaneously after entering a position).
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How Markets Work
Execution flow
When you click Buy or Sell, your order travels through a chain of systems before reaching the market. Understanding this journey explains why prices can differ from what you saw, why fills take time, and why order routing matters.
The journey of a stock order
You place order
>
Your broker
>
Order routing
>
Exchange or ECN
>
Order book matching
>
Fill confirmed
Key concepts in execution
Order bookA live list of all outstanding buy and sell orders at every price level. Buyers are listed on the bid side, sellers on the ask side. When a buyer and seller agree on price, the trade executes.
Market makerA firm that continuously provides buy and sell quotes to ensure liquidity. They profit from the bid-ask spread and take the other side of your trade when no other participant is available.
PFOFPayment For Order Flow. Many retail brokers sell your order to a market maker instead of sending it directly to an exchange. The market maker executes your trade and profits from the spread. This is how "commission-free" brokers make money.
ECNElectronic Communication Network. A system that matches buyers and sellers directly without a market maker. Often provides better prices but may charge a small commission per share.
LatencyThe time between placing your order and its execution. Retail orders take milliseconds. High-frequency trading firms co-locate servers at exchanges to gain microsecond advantages.
Options order execution
Options orders route to options exchanges (CBOE, NYSE Arca, Nasdaq PHLX). Because options are less liquid than stocks, best execution often means placing a limit order at the midpoint of the bid-ask spread and adjusting by a cent or two if needed. Market orders on options almost always result in poor fills.
Best execution rule: Brokers are legally required to seek the best reasonably available price for your order. In practice, use limit orders to ensure you control your price rather than relying entirely on your broker's routing.
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How Markets Work
Price discovery
Price discovery is the process by which markets find the fair value of an asset through the interaction of buyers and sellers. Every trade that occurs is a negotiation that establishes what a willing buyer and willing seller agree a stock is worth at that moment.
No single person or institution sets a stock price. It emerges continuously from millions of buy and sell orders interacting on exchanges around the world. Price is always a real-time consensus opinion on value.
What moves prices
Earnings
Company results
Quarterly earnings beats or misses are the single largest driver of individual stock price moves.
More buyers than sellers pushes price up. More sellers than buyers pushes price down.
Sentiment
Crowd psychology
Fear and greed move prices beyond rational value in the short term. Markets can be irrational.
Liquidity
Available capital
When capital is plentiful, prices rise broadly. When capital tightens (rising rates), prices fall.
Reading a stock quote
Last price
$195.50
Most recent trade
Bid
$195.48
Best buy offer now
Ask
$195.52
Best sell offer now
Efficient markets
The efficient market hypothesis argues that prices already reflect all available public information. If true, beating the market consistently is nearly impossible for retail traders.
Market inefficiencies
In practice, short-term mispricings exist due to emotion, information delays, and liquidity gaps. Options traders can exploit these briefly before prices correct.
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Key Metrics
Volume
Volume is the total number of shares (or contracts) traded during a specific time period. It is one of the most important confirmation tools in trading because it tells you how many participants agreed on the current price.
Price moves backed by high volume are more meaningful and more likely to continue. Price moves on low volume are suspect, less reliable, and more likely to reverse. Volume is the conviction behind the price.
How to interpret volume
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Price rises on high volume. Strong buying pressure. Many participants agree the stock is worth more. Bullish signal. Move is more likely to continue.
Bullish
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Price rises on low volume. Weak buying. Few participants driving the move. Could be temporary. May reverse when volume returns.
Suspect
-
Price falls on high volume. Heavy selling pressure. Bearish signal. Many participants exiting simultaneously. Move likely to continue.
Bearish
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Price falls on low volume. Weak selling. Could be temporary profit-taking. Not a panic sell. More likely to stabilize.
Watch
Key volume metrics
Average daily volume
ADV
The average number of shares traded per day over 20-90 days. Your position should not exceed 1-5% of ADV to avoid moving the market.
Relative volume
RVOL
Today's volume compared to average. RVOL of 3x means today is trading at 3 times normal. Often signals a catalyst has hit the stock.
Open interest
OI
For options specifically. The number of outstanding contracts. High OI indicates liquidity and tighter spreads. Low OI means wider spreads and harder to exit.
Volume vs OI
Day vs Total
Options volume is today's contracts traded. Open interest is total outstanding. Volume greater than OI suggests new positions being opened, not just speculation.
Volume breakouts: When a stock breaks a key resistance level on volume that is 2x or more its average, the breakout is considered confirmed and more likely to sustain. A breakout on below-average volume is a warning signal.
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Key Metrics
Market capitalization
Market capitalization (market cap) is the total market value of a company's outstanding shares. It is calculated by multiplying the current share price by the total number of shares outstanding. It tells you the size of a company as valued by the stock market.
Market cap formula
Market Cap = Share Price x Total Shares Outstanding
Apple at $195 x 15.4 billion shares = approximately $3 trillion market cap
Market cap categories
Mega cap
$200B+
Apple, Microsoft, NVIDIA. Most liquid, most stable. Options are very liquid with tight spreads.
Large cap
$10B to $200B
Established companies, widely covered. Good options liquidity. Lower volatility than small caps.
Mid cap
$2B to $10B
Growing companies with some market presence. Moderate options liquidity. Higher potential growth.
Small cap
$300M to $2B
Smaller companies, higher risk and reward. Options spreads are often wide. Less analyst coverage.
Micro cap
Under $300M
Very small, illiquid, speculative. Avoid for options trading. Spreads are prohibitively wide.
Why market cap matters for options traders
LiquidityLarger market cap stocks have more options contracts traded daily, meaning tighter bid-ask spreads and easier entries and exits. This directly reduces your trading costs.
VolatilitySmaller companies tend to have higher implied volatility (more expensive options) and more dramatic price swings. Higher potential profit, but also higher risk.
Analyst coverageLarge caps have hundreds of analysts. Information is widely known and priced in quickly. Small caps may have fewer eyes watching, creating occasional mispricings.
Index membershipLarge caps in the S&P 500 experience extra buying pressure from index funds and ETFs that must hold them. This creates a natural support floor that smaller companies lack.
For beginner options traders: Stick to large and mega cap stocks for options trading. The liquidity keeps spreads tight, the options market is deep, and the price moves are more predictable. Leave micro and small cap options to experienced traders.
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Orders and Execution Quiz
Test your orders and execution knowledge
16 questions across all topics. Score 11 or higher to pass.
