The Greeks are a small set of numbers that describe how an option's value behaves. You don't need the math to use them — you just need to know what each one tells you. This chapter explains the four Greeks you'll see most often, what implied volatility means, and then the big one for reading the whole market: gamma exposure (GEX) and the gamma regime.

These terms show up across Option Trades, Rank Contracts, and Rank Symbols. This is the page they point back to.

The four Greeks, in plain words

Think of the Greeks as four different "sensitivity dials." Each one answers a single question about how an option reacts to the world changing.

Each Greek answers one question about how an option reacts.

Delta — direction and "how much"

Delta measures how much an option's price moves when the stock moves $1.

• Calls have positive Delta (between 0 and 1) — they gain when the stock rises.
• Puts have negative Delta (between -1 and 0) — they gain when the stock falls.

A Delta of 0.50 means the option moves about $0.50 for every $1 in the stock. Delta is also a rough shorthand for "how stock-like" the position is. Across many trades, TradingFlow rolls Delta up into DEX (delta exposure) to show net bullish or bearish positioning — see Options & Flow Concepts.

Gamma — how quickly Delta changes

Gamma tells you how fast Delta itself changes as the stock keeps moving. High Gamma means an option's behavior can shift quickly — it can go from barely reacting to moving almost dollar-for-dollar in a short run. Gamma is highest for options near the current price and close to expiration. This single dial is what powers the GEX section below.

Theta — the cost of waiting

Theta is the amount an option loses each day simply because time is passing ("time decay"). Options are wasting assets: all else equal, they're worth a little less tomorrow than today. Theta is the price you pay to hold an option, and it speeds up as expiration approaches.

Vega — sensitivity to fear and calm

Vega measures how much an option's price moves when implied volatility changes. When markets get nervous, IV rises and options get more expensive — that's Vega at work, even if the stock hasn't moved at all yet.

Implied Volatility (IV)

Implied Volatility (IV) is the market's expectation of how much a stock will move going forward, baked into option prices.

• High IV = options are expensive, and the market expects bigger swings.
• Low IV = options are cheaper, and the market expects calmer conditions.

IV often jumps before a known event (earnings, an FDA decision, a Fed meeting) and then collapses right after — this drop is called "IV crush," and it can hurt option buyers even when they guessed the stock's direction correctly.

IV Rank and IV Percentile

A raw IV number is hard to judge on its own — is 40% high or low? That depends on the stock. Two tools fix this by comparing today's IV to the past year:

• IV Rank asks: where does today's IV sit between this stock's lowest and highest IV over the last year? An IV Rank near 100 means IV is close to its yearly high; near 0 means it's close to its yearly low.
• IV Percentile asks: what share of days in the past year had IV lower than today? An IV Percentile of 80% means IV has been lower than this on 80% of days — today is relatively elevated.

Both turn one number into context. As a rough habit: high IV Rank/Percentile favors selling premium (options are pricey); low IV Rank/Percentile favors buying (options are cheap).

Gamma Exposure (GEX) — the market's "shock absorber"

This is the most powerful idea on the page. Gamma Exposure (GEX) is the total Gamma of all the options outstanding, viewed from the perspective of the market makers ("dealers") who sit on the other side of those trades.

Why does this matter to you? Dealers don't want to bet on direction — they hedge. To stay neutral, they constantly buy and sell the underlying stock as it moves. The direction of that hedging flips the market's whole character. That's the gamma regime.

The gamma regime decides whether dealer hedging calms the market or stirs it up.

Positive gamma — a calmer market

In a positive gamma regime, dealer hedging works against the move:

• Stock rises → dealers sell stock → pushes back down.
• Stock falls → dealers buy stock → props it up.

The effect is stabilizing. Markets tend to be range-bound and mean-reverting; dips get bought and sharp rallies tend to fade. Big surprises can still happen, but day-to-day moves are usually smaller.

Negative gamma — a jumpier market

In a negative gamma regime, dealer hedging works with the move and makes it bigger:

• Stock rises → dealers buy stock → pushes it higher still.
• Stock falls → dealers sell stock → drives it lower still.

The effect is destabilizing. Markets trend harder, moves can snowball, and volatility tends to be elevated. This is the backdrop for sharp, fast runs and abrupt drops.

The GEX Environment badge

You don't have to calculate any of this. TradingFlow reads the gamma regime for each stock and shows it as a GEX Environment badge so you can tell at a glance whether the backdrop is more "calm and range-bound" or "jumpy and trending." See it in action on Rank Symbols, and visit the live tool at Rank Symbols.

Related structure — call walls, put walls, gamma squeezes, and where these levels sit on the chain — is covered in Option Chain & OI.

How to actually use this

• Reading a single trade? Delta tells you direction and size; Theta and Vega tell you what the holder is up against over time.
• Sizing up a stock's options? Check IV Rank/Percentile to see if options are cheap or expensive right now.
• Trying to read the whole tape? Glance at the gamma regime first. Positive gamma says "expect the range to hold"; negative gamma says "expect bigger, faster moves."

A reminder: these are probabilistic signals about market structure, not guarantees. News and fundamentals can override them at any time.

What to do next

Now that you can read the Greeks and the gamma regime, see how these levels stack up on the Option Chain & OI — where open interest, call walls, and put walls show you the price levels the whole market is watching.

希腊字母（Greeks） 是一小组用来描述期权价值如何变化的数字。你不需要懂背后的数学，只要知道每个字母告诉你什么就够了。本章会讲清你最常见到的四个希腊字母、隐含波动率 是什么，最后再讲读懂整个市场的关键：伽马敞口（GEX） 与 伽马环境（gamma regime）。

这些术语会出现在 期权交易、合约排行 和 标的排行 中。它们都指向本页。

四个希腊字母，一句话说清

可以把希腊字母想成四个不同的"灵敏度旋钮"。每个旋钮回答一个关于期权如何对外界变化做出反应的问题。

每个希腊字母回答一个关于期权如何反应的问题。

Delta —— 方向与"动多少"

Delta 衡量当股价变动 $1 时，期权价格会跟着变动多少。

• 看涨期权（Call） 的 Delta 为正（0 到 1 之间）—— 股价上涨时获利。
• 看跌期权（Put） 的 Delta 为负（-1 到 0 之间）—— 股价下跌时获利。

Delta 为 0.50 意味着股价每变动 $1，期权大约变动 $0.50。Delta 也可以粗略理解为"这个仓位有多像股票"。在大量交易上，TradingFlow 会把 Delta 汇总成 DEX（delta 敞口），用来展示净看多还是看空的持仓——详见 期权与资金流概念。

Gamma —— Delta 变化有多快

Gamma 告诉你随着股价持续移动，Delta 本身变化得有多快。Gamma 高，意味着期权的表现会迅速改变——可能在短短一段行情里，从几乎不反应变成几乎与股价同步变动。越接近当前价格、越临近到期的期权，Gamma 越高。正是这个旋钮，驱动了下文的 GEX。

Theta —— 等待的成本

Theta 是期权仅仅因为时间流逝、每天损失的金额（"时间损耗"）。期权是会损耗的资产：其他条件不变，它明天会比今天稍微便宜一点。Theta 就是你持有期权所付出的代价，而且越临近到期，损耗越快。

Vega —— 对恐慌与平静的敏感度

Vega 衡量当 隐含波动率 变化时，期权价格会跟着动多少。当市场变得紧张，IV 上升，期权变贵——这就是 Vega 在起作用，哪怕股价还一动没动。

隐含波动率（IV）

隐含波动率（IV） 是市场对一只股票未来波动幅度的预期，被嵌进了期权价格里。

• IV 高 = 期权贵，市场预期会有更大的波动。
• IV 低 = 期权便宜，市场预期行情更平静。

IV 常常在已知事件（财报、FDA 决定、美联储议息）之前 飙升，然后在事件之后立刻塌陷——这种下跌叫 "IV crush（波动率坍缩）"，即便期权买家方向猜对了，也可能因此亏钱。

IV Rank 与 IV Percentile

单看一个 IV 数字很难判断——40% 算高还是低？这要看具体的股票。有两个工具能解决这个问题，它们把今天的 IV 与 过去一年 做对比：

• IV Rank 问的是：今天的 IV 落在这只股票过去一年 最低 和 最高 值之间的什么位置？IV Rank 接近 100 表示 IV 接近年度高点；接近 0 表示接近年度低点。
• IV Percentile 问的是：过去一年里，有 多少比例的交易日 IV 比今天 更低？IV Percentile 为 80% 表示有 80% 的日子 IV 比现在低——今天相对偏高。

两者都把一个孤零零的数字变成了有参照的信息。一个粗略的习惯：IV Rank/Percentile 高，更适合 卖出 期权（期权贵）；IV Rank/Percentile 低，更适合 买入（期权便宜）。

伽马敞口（GEX）—— 市场的"减震器"

这是本页最强大的概念。伽马敞口（GEX） 是所有未平仓期权的总 Gamma，但要从坐在这些交易对手方的做市商（"庄家/dealers"）的角度来看。

这跟你有什么关系？做市商不想赌方向——他们要 对冲。为了保持中性，他们会随着股价移动不断买卖标的股票。而这种对冲的方向，会彻底改变市场的整体性格。这就是 伽马环境。

伽马环境决定了做市商的对冲是在平抑市场，还是在火上浇油。

正伽马 —— 更平静的市场

在 正伽马 环境下，做市商的对冲与行情 反向 用力：

• 股价上涨 → 做市商 卖出 股票 → 把价格压回去。
• 股价下跌 → 做市商 买入 股票 → 把价格托起来。

效果是 稳定的。市场倾向于区间震荡、均值回归；回调会被买入，急涨往往后继乏力。大意外仍可能发生，但日内波动通常更小。

负伽马 —— 更跳动的市场

在 负伽马 环境下，做市商的对冲与行情 同向 用力，把波动放得更大：

• 股价上涨 → 做市商 买入 股票 → 把价格推得更高。
• 股价下跌 → 做市商 卖出 股票 → 把价格压得更低。

效果是 不稳定的。市场趋势更强，行情可能滚雪球，波动往往偏高。这正是那种又急又快的拉升、以及突如其来的暴跌发生的背景。

GEX Environment 徽章

这些你都不用自己算。TradingFlow 会读出每只股票的伽马环境，并以 GEX Environment 徽章的形式展示出来，让你一眼就能看出背景是更偏"平静、区间震荡"还是"跳动、趋势性"。可在 标的排行 中看到它的实际效果，也可前往线上工具 Rank Symbols。

相关的结构——看涨墙（call wall）、看跌墙（put wall）、伽马挤压（gamma squeeze），以及这些价位在期权链上的位置——在 期权链与未平仓（OI） 中讲解。

实际怎么用

• 在看一笔交易？ Delta 告诉你方向和规模；Theta 和 Vega 告诉你持有者随时间要面对什么。
• 在评估一只股票的期权？ 看 IV Rank/Percentile，判断现在期权是便宜还是贵。
• 想读懂整张盘面？ 先瞄一眼伽马环境。正伽马在说"预计区间能守住"；负伽马在说"预计会有更大、更快的波动"。

提醒一句：这些是关于市场结构的 概率性 信号，不是保证。新闻和基本面随时可能盖过它们。

下一步做什么

现在你已经能读懂希腊字母和伽马环境了，接着去看这些价位在 期权链与未平仓（OI） 上是如何堆叠的——未平仓量、看涨墙和看跌墙会告诉你整个市场都在盯着哪些价位。