Gaps and Overnight Risk

You entered a stock at ₹500 from your ₹5,00,000 account. Stop loss was placed at ₹482, below the swing low. Overnight, the company announces disappointing quarterly results. The stock opens the next morning at ₹468.

If you had placed a Stop Loss Market (SL-M) order, it would have been triggered at the open and you would have sold at ₹448 — a loss of ₹32 per share instead of the planned ₹18. If you had placed a Stop Loss Limit (SL-L) order at ₹462, it would not have triggered at all because price never reached ₹462. You would still be holding a position down ₹32 with no exit executed.

This is gap risk. It is the price swing traders pay for holding positions overnight. Understanding and managing it is not optional.

By the end of this chapter, you will be able to:

• Explain how overnight gaps occur and why stop losses cannot fully protect against them.
  
• Apply two specific techniques to reduce gap risk exposure.
  
• Identify the situations where gap risk is highest and adjust position sizing accordingly.
  

How Gap Risk Works and How to Manage It

A gap occurs when the opening price of a session is significantly different from the previous close. In India, this includes overnight global events, RBI announcements outside market hours, company earnings releases, and promoter activity news. SL-M orders execute at the first available market price — on a gap, that is the open price, which can be far from the stop level.

The first technique is to size for gap risk. When holding into a known risk event — quarterly earnings, RBI announcement, Union Budget — size the position at half of normal. Even if a gap doubles the effective loss, the total rupee impact stays within tolerable limits.

The second is to avoid holding through known catalysts. Quarterly earnings are the most predictable source of large gaps. If a stock is due to be announced within the next two sessions, consider closing before the announcement.

A shopkeeper in a market that has a history of occasional flooding does not remove the shop. But they raise the merchandise off the floor before monsoon season and reduce inventory on days when heavy rain is forecast. Swing traders manage gap risk the same way: they do not stop trading overnight; they reduce exposure when known risks are highest.

Common Mistakes

Mistake 1: Assuming a stop loss fully protects against gap risk

SL-M orders execute at the open price on a gap day, which can be significantly worse than your planned stop level. SL-L orders may not execute at all if price opens beyond the limit.

Mistake 2: Holding full size into every earnings announcement

Quarterly earnings are predictable risk events. Holding full size into earnings when the setup could be re-entered afterwards is choosing to accept maximum gap risk unnecessarily.

Key Takeaways

• Overnight gaps can open price far beyond your stop loss level. SL-M orders protect against gaps but at a worse price. SL-L orders may not protect at all.
• Manage gap risk by reducing position size around known catalyst events — especially quarterly earnings.
• The goal is not to eliminate gap risk but to ensure that even a worst-case gap does not do disproportionate damage to the account.

Assignment

Starting today, track all upcoming risk events for the next four weeks in a simple calendar: quarterly results dates for stocks on your watchlist, upcoming RBI MPC meetings, and any key global events that could cause overnight gaps.

For each position you are considering, check whether a scheduled event falls within the likely holding period. Write your plan for each: will you avoid the event, reduce size, or exit before it? Keep this risk calendar updated throughout the course.

In the next chapter, we cover position sizing — the formula that determines exactly how many shares to buy based on risk, not on conviction.

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