What are stock options?

Stock options are contracts that give the holder the right, but not the obligation, to buy (call) or sell (put) a stock at a specific price (strike price) before a certain date (expiration). They are used for speculation, hedging, and income generation.

What are the options Greeks?

The Greeks are sensitivity measures for options pricing. Delta measures price sensitivity to the underlying stock, gamma measures the rate of change of delta, theta measures time decay, and vega measures sensitivity to implied volatility changes.

What is GEX and how is it used in trading?

GEX (gamma exposure) measures the total gamma held by options market makers across all strikes. Positive GEX environments tend to suppress volatility as dealers hedge by selling into rallies and buying dips. Negative GEX can amplify moves. Traders use GEX levels to anticipate market behavior and set trading ranges.

What are 0DTE options?

0DTE (zero days to expiration) options are contracts that expire on the same day they are traded. They offer high leverage and rapid time decay, making them popular for intraday traders but extremely risky. They now account for a significant portion of daily SPX options volume.

Options Trading Education — Basics to GEX Strategy

Foundations · Level 1

📌 Options Basics

An option is a contract that gives the buyer the right, but not the obligation, to buy or sell 100 shares of a stock at a specific price (the strike price) before a specific date (the expiration).

Calls vs. Puts

A call option gives you the right to BUY shares at the strike price. You buy calls when you expect the stock to go up. A put option gives you the right to SELL shares at the strike price. You buy puts when you expect the stock to go down.

The Four Basic Positions

Long Call 📈

BullishDefined RiskUnlimited Profit

Buy a call when you expect the stock to rise significantly above the strike price before expiration. Max loss = premium paid. Max profit = unlimited (stock goes to infinity).

Long Put 📉

BearishDefined RiskHigh Profit Potential

Buy a put when you expect the stock to fall below the strike before expiration. Max loss = premium paid. Max profit = strike price minus zero (stock goes bankrupt).

Short Call 📊

Bearish/NeutralPremium SellerUnlimited Risk

Sell a call when you expect the stock to stay below the strike. You collect premium upfront. Max profit = premium received. Risk is theoretically unlimited. Always use spreads to cap risk.

Short Put 💰

Bullish/NeutralPremium SellerHigh Probability

Sell a put when you expect the stock to stay above the strike. Collect premium. Most popular income-generating strategy. Equivalent to a cash-secured put — you're willing to buy the stock at the strike.

Foundations · Level 2

Δ The Greeks — Options Sensitivity Measures

The Greeks measure how much an option's price changes in response to different factors. Understanding them is essential for managing positions and selecting the right strikes.

ΔDeltaHow much the option price changes per $1 move in the stock. Calls have positive delta (0 to 1), puts have negative delta (-1 to 0). ATM options have delta ≈ 0.50. Delta also approximates the probability the option expires in the money.

ΓGammaThe rate of change of delta. High gamma means delta changes quickly as price moves. ATM options near expiration have the highest gamma. Gamma is what GEX measures at a market level — it determines whether dealers amplify or dampen price moves.

ΘThetaTime decay — how much the option loses per day as it approaches expiration. Theta is negative for buyers (they lose value with time) and positive for sellers (time works in their favor). ATM options decay fastest in the last 30 days — the "sweet spot" for selling premium.

ν (Vega)VegaSensitivity to implied volatility. A $1 increase in IV increases the option price by vega. Buy options when IV is low (cheap), sell when IV is high (expensive). Vega is highest for long-dated ATM options and collapses near expiration.

Advanced · Level 4

Γ GEX Trading Strategy

Gamma Exposure (GEX) is the aggregate gamma held by options dealers. It predicts how dealers will hedge — and therefore where market support and resistance will form.

Two Market Regimes

Positive Gamma Regime

Low VolatilityMean RevertingPremium Selling

Dealers are long gamma. They buy dips and sell rallies — suppressing volatility. Price tends to pin between the call wall (resistance) and put wall (support). Best strategies: iron condors, credit spreads, short straddles near OPEX.

Negative Gamma Regime

High VolatilityTrendingDirectional Plays

Dealers are short gamma. Their hedging amplifies price moves — creating trending, volatile conditions. Best strategies: buying directional options near the gamma flip, debit spreads in the direction of the trend, reduced position sizing overall.

The Gamma Flip Trading Setup

The gamma flip is the most actionable level in GEX analysis. When price crosses the flip — especially near OPEX — the regime changes and volatility character shifts. Watch for: a sustained close above the flip = positive gamma (range-bound), a break below = negative gamma (volatile trending).

Advanced · Level 4

⚡ 0DTE Options — Same-Day Expiration

0DTE (zero days to expiration) options are contracts that expire on the day you trade them. SPY and QQQ have options expiring every trading day. They've become the most traded options instrument, now accounting for over 40% of daily SPY options volume.

Why 0DTE Has Exploded

0DTE offers extreme leverage with defined risk. A $1.50 0DTE SPY call can become worth $10 if SPY moves 1% in the right direction. The same $150 investment on a weekly option might only become $300. The tradeoff: most 0DTE options expire worthless — theta decays to zero in hours, not days.

GEX and 0DTE

0DTE trading is most powerful when combined with GEX analysis. In positive gamma, dealers actively suppress moves around the call/put walls — making 0DTE spreads between the walls high-probability. In negative gamma, 0DTE directional plays near the gamma flip can capture amplified moves.

⚠️ 0DTE Risk Warning

0DTE options can lose 100% of their value within hours. They are not suitable for beginners. Start with weekly or monthly options to learn how Greeks behave before trading same-day expiration. Always use defined risk (spreads) for 0DTE — never naked options.