What is Sell to Open vs. Sell to Close?
If you are new to options trading, simply placing an order can feel like learning a foreign language. Unlike buying normal stocks where you just hit "Buy" or "Sell," options require you to specify exactly what kind of transaction you are making.
Pressing the wrong button doesn't just cancel your trade—it can accidentally double your risk and cost you thousands.
The most common point of confusion for new traders is understanding the difference between sell to open vs sell to close. While both buttons result in you selling an options contract, they do two entirely different things to your portfolio. Let's break down exactly what each term means and when you should use them.
Key Takeaways
- ✓Sell to Open means you are writing a new options contract and collecting premium upfront. You are starting a brand-new short position.
- ✓Sell to Close means you are exiting an options contract you previously bought. You are ending an existing long position.
- ✓Both involve selling, but they have opposite effects on your account: one adds a new obligation, the other removes one.
- ✓Your broker requires this specific phrasing because it needs to know whether you're opening new risk or closing existing risk.
- ✓Mastering these four brokerage order types — Buy to Open, Buy to Close, Sell to Open, and Sell to Close — is the foundation of every options trade.
The Shift in Modern Trading: Following the Smart Money
Let's face it: the old way of doing trading is gone. Instead of using traditional indicators, modern traders follow institutions, hedge funds, politicians, and market makers to see where they are investing and copy their trades directly. There are so many trades happening every single day where they are not losing any money; the majority of the time, they are winning.
The Basics: "Opening" vs "Closing" a Position
Before we look at the "selling" part, you need to understand the second half of the phrase: Open vs. Close.
- Opening a position means you are creating a brand new trade. You currently hold zero contracts, and you are entering the market to start a new position.
- Closing a position means you are exiting a trade you are already in. You are tying up loose ends to lock in a profit or take a loss.
What is "Sell to Open" (STO)?
When you select Sell to Open, you are becoming an options writer (or seller). You are creating a brand-new short position. In this scenario, you do not currently own the options contract. Instead, you are writing it into existence and selling it to someone else. Because you are the seller, you collect a premium (cash) upfront, which is credited to your account immediately. However, you also take on an obligation.
Play with the sliders below to see how selling a call to open changes your profit structure in real-time:
Options Strategy Presets
Real-World Example: Selling a Covered Call on Robinhood
Let's say you own 100 shares of Apple (AAPL), currently trading at $195 per share. You think the stock will stay flat or rise slightly over the next 30 days, and you want to generate some extra income from your shares.
- Open your brokerage app and navigate to the AAPL options chain.
- Select "Sell" as your action, and choose Sell to Open.
- The order fills. You collect, say, $3.50 per share in premium — that's $350 cash deposited into your account immediately.
Your trade is now active. You've written a covered call. You used Sell to Open because this was a new position.
What is "Sell to Close" (STC)?
When you select Sell to Close, you are exiting an options trade that you previously bought. You would only use this button if you had previously used Buy to Open. You own an options contract, and now you want to get rid of it. By selling to close, you are selling the contract back to the market to close out your position.
Real-World Example: Taking Profits on a Tesla Call
- Monday (Buy to Open): You buy 1 TSLA Call option for $4.00 ($400 total) because you think the stock will go up.
- Thursday (Sell to Close): Tesla stock shoots up, and your Call option is now worth $11.50. To lock in your gains, you select Sell to Close.
- The order fills at $11.50. You receive $1,150 back into your account ($750 profit).
The trade is now fully closed.
Sell to Open vs Sell to Close: Side-by-Side Comparison
| Feature | Sell to Open (STO) | Sell to Close (STC) |
|---|---|---|
| Action | Write (create) a new options contract | Sell an options contract you already own |
| Purpose | Start a new short position & collect premium | Exit an existing long position |
| Account Impact | Adds a new obligation to your account; you receive premium | Removes an existing position; you receive sale proceeds |
| Prior Position | You do NOT own this contract beforehand | You DO own this contract (bought via Buy to Open) |
| Example | You sell an AAPL $200 Call to collect $350 in premium | You sell your TSLA $185 Call (bought at $400) for $1,150 |
The Quick Summary
- Use Sell to Open if: You want to collect premium, write a covered call, write a cash-secured put, or start a brand new short position.
- Use Sell to Close if: You already own an option and you want to sell it to take your profits or cut your losses.
Why Brokers Require This Phrasing
You might wonder why brokers don't just have a simple "Sell" button. It is because options accounts allow traders to hold multiple complex positions at once. A broker needs to know if the contract you are selling is meant to cancel out one you already own (closing), or if you are trying to take on new risk by writing a new one (opening).
Mastering these four little words is your first major step toward trading options confidently with PolyTICK.
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