ITM (in the money), OTM (out of the money) and ATM (at the money) describe where the stock stands relative to your option's strike right now. ITM means the option has real value if exercised this second; OTM means it is running purely on hope; ATM means the stock is sitting on the line.
For a call, in the money means the stock is above the strike: you could buy at the strike and sell at the market for more. For a put it flips: in the money means the stock is below the strike. The labels are not permanent, either. One move in the stock and your option changes camps without asking you.
The numbers
One stock at $100, five different options. Same market, same second. The label depends only on where the strike sits and which direction the contract points.
| Option | Label | Intrinsic value |
|---|---|---|
| $95 call | ITM | $5.00 |
| $100 call | ATM | $0 |
| $105 call | OTM | $0 |
| $105 put | ITM | $5.00 |
| $95 put | OTM | $0 |
Note what intrinsic value ignores: the OTM $105 call still trades around $3.00 with a month left. That entire price is time value, the market's fee for what could still happen. The split is explained in option premium.
Where it bites
Finishing ITM is not the same as making money. The classic beginner reading: "my option expired in the money, so I won." The $105 call you paid $3.00 for finishes with the stock at $106. It is ITM, worth $1.00, and you lost $200 of your $300. The label measures the stock against the strike; your profit is measured against what you paid.
OTM is cheap because it is losing. An out-of-the-money option is, by definition, an option that pays nothing if the world stops moving. The low price is not an inefficiency you discovered. It is the market telling you the odds.
Short and ITM near expiry means shares move. If you sold an option and it sits in the money at expiry, it gets exercised against you and real stock changes hands, whether or not that was your plan. That handover is called assignment, and it is the part of "income" strategies nobody advertises.
Go feel it
The labels come alive when you pick strikes on a live simulated stock and watch options drift in and out of the money before your eyes. That is exactly what Lesson 3: The Strike is for.
Related concepts: strike price · option premium · theta decay