Explore how to read an ATM straddle chart and understand option premium decay in NIFTY and SENSEX expiry trading. This guide explains how an ATM straddle is calculated using the combined premiums of an at-the-money call and put, and why its movement can reveal changes in market volatility, theta decay, and expiry-day risk.

Learn to identify four important ATM straddle chart patterns: smooth premium decay, step-down movements, flat shelves, and sudden spikes. Understand what these patterns may indicate about market conditions, implied volatility, and the risks faced by short straddle traders.

The article also explains the three key phases of expiry-day trading: morning repricing, mid-session premium decay, and the final-hour collapse. It highlights how gamma risk increases near expiry and why sudden premium spikes can threaten option-selling strategies.

Discover how strike rolls can create misleading chart movements, why VIX and synthetic futures provide useful confirmation, and how comparing front-week and back-week straddles can add context to volatility analysis.

Whether you trade NIFTY or SENSEX options, this guide offers a practical framework for interpreting straddle charts, tracking premium decay, identifying warning signs, and improving your options research. The examples are educational and should not be treated as guaranteed trading signals.