Where should a beginner place a stop loss?

What a stop loss actually does

When you open a position, you can attach a second instruction for your broker: if price falls to this level, close my position automatically. That instruction is the stop loss. You do not have to watch the screen. If the market moves against you, the position closes on its own and the loss stops there.

The real reason it exists is psychological rather than technical. Without a stop loss, the most common reaction to a losing trade is to wait for it to come back. A small loss quietly becomes a large one, because nobody defined in advance the point where the idea is admitted to be wrong.

Where beginners place it (and where they should)

The classic beginner mistake is the arbitrary stop: placing it 2% below the entry because 2% sounds reasonable. The market does not know where you bought. A stop loss earns its keep when it sits just beyond a real chart level, for example slightly below a support zone.

The logic is simple: if price breaks through support, the scenario you traded on has been invalidated. So the stop is not a random number, it is the point where your idea is proven wrong. You find that level first, and only then decide how large a position to open, never the other way around.

• Wrong: a stop at a random percentage below your entry.
• Right: a stop just beyond support, resistance or another real level.
• The stop answers one question: where is my scenario invalidated?
• Level first, position size second.

Worked example: risk per trade with real numbers

Say you have a $1,000 account and you follow a basic risk management rule: never risk more than 1% to 2% of the account on a single trade. At 2% risk, your maximum acceptable loss is $20.

You are watching a stock at $50 with support at $48. You place the stop loss at $47.50, just below the support level. Risk per share is $50 minus $47.50, which is $2.50. Divide: $20 maximum loss divided by $2.50 risk per share equals 8 shares. If the stop is hit, you lose roughly $20, the 2% you decided on in advance, and your account survives to take the next trade.

Slippage: why a stop is not an absolute guarantee

There is one detail worth knowing. When price reaches your level, the stop order executes at the next available price, not necessarily exactly at your level. The difference is called slippage. In calm markets it is usually tiny, but during sharp moves, for example right after major news, the fill can land noticeably below your stop.

That does not make stop losses useless, it means the real loss can turn out slightly larger than the theoretical one, which is worth building into your expectations. In Tradebook you practice placing stop losses on real chart scenarios, so the habit forms before real money is ever involved.