Vanna and Charm:
The Forces That Move Options After the Open

Beyond First-Order Greeks

Most options education stops at the first-order Greeks: delta, gamma, theta, vega. These describe a static snapshot. In reality, options risk shifts constantly — not just because the underlying price moves, but because implied volatility moves and time passes. The Greeks that capture these second-order effects are where the real structural market flows originate.

Vanna and Charm are two of the most important second-order Greeks for understanding intraday SPY market structure. They explain moves that have no obvious catalyst, create reliable time-of-day patterns, and drive some of the most frustrating-to-trade environments: the low-vol grind up that refuses to pull back.

What is Vanna?

Vanna measures how delta changes when implied volatility changes.

Why does this matter for hedging? Dealers delta-hedge continuously. When IV rises, the delta of their options positions changes even if the underlying hasn't moved. That changed delta creates new exposure that needs to be hedged — mechanically, regardless of any view on direction.

Option Type	IV Change	Delta Change	Dealer Hedging Action
OTM Call	IV ↑	Delta increases (more likely ITM)	Buy underlying to hedge
OTM Put	IV ↑	Delta decreases (more negative)	Sell underlying to hedge
OTM Call	IV ↓	Delta decreases (less likely ITM)	Sell underlying to hedge
OTM Put	IV ↓	Delta increases (less negative)	Buy underlying to hedge

In a market dominated by put buying (as SPY typically is), falling IV means dealers need to buy the underlying to re-hedge their put books. This is directionally bullish — and it happens mechanically, without any fundamental catalyst.

How Vanna Creates Directional Pressure

The most important Vanna dynamic in SPY is what happens after a volatility spike. When IV gets elevated — during a selloff, before a major event, or during uncertainty — dealers accumulate large short-put positions with large negative delta hedges. They're holding short underlying to offset those put exposures.

When IV reverts lower, those puts lose delta rapidly. Dealers no longer need as much short exposure. They buy back the underlying to re-flatten. This buying pressure has nothing to do with earnings or economics — it's pure mechanical re-hedging.

Vanna flows are most powerful under two conditions:

• High absolute IV: The higher the IV, the larger the dealer delta positions built up. More to unwind = more flow on the way back down.
• Fast IV mean-reversion: If IV drops 3 points in a morning session, that Vanna flow is compressed into a short time window and has outsized price impact.

What is Charm?

Charm (also called delta decay, or DdeltaDtime) measures how delta changes as time passes, holding everything else constant.

As expiration approaches, out-of-the-money options lose delta. An OTM call that had a delta of 0.25 in the morning might have a delta of 0.18 by mid-afternoon — not because SPY moved, but because time passed. Dealers who were long the underlying to hedge that 0.25 delta now have too much hedge. They need to sell the excess.

How Charm Drives Intraday Drift

Charm is a time-based flow, so it's relatively predictable in terms of when it acts:

• Pre-market / open: Options are repriced after overnight gaps. Charm flows are reset and relatively small in the first hour.
• Midday: Steady, low-impact Charm decay across all expiries. Market often quietest here.
• Final 90 minutes: Delta decay accelerates sharply as 0DTE options approach expiry. Large OI at nearby strikes creates concentrated Charm flow — often driving the "drift" that closes the session near a key strike.

The key distinction: Charm doesn't require a price move to trigger hedging. Gamma hedging happens because SPY moved. Charm hedging happens because time passed. This is why expiration days sometimes see persistent gravitational pull toward a specific level with no obvious news.

The Vanna Squeeze Pattern

The "Vanna squeeze" is one of the most recognizable patterns in SPY. Here's the setup:

1. SPY sells off sharply. VIX spikes. Traders buy puts heavily for protection.
2. Dealers absorb put buying and hedge with short SPY exposure. IV is elevated. Vanna positioning is large and bearish.
3. The catalyst fades. Market stabilizes.
4. IV begins to mean-revert lower. Dealers start reducing short SPY hedges as put deltas decay.
5. The buying from Vanna unwind creates buying pressure → SPY moves higher → more delta decay → more Vanna buying. A feedback loop.
6. Market grinds higher with no news, low realized volatility, tight intraday ranges.

Vanna + Charm Together

In practice, Vanna and Charm often work in the same direction. After a volatile week with elevated IV and large put OI nearby, both flows can push bullish simultaneously:

• Vanna says: if IV drops through the session, dealers will be systematically buying to reduce short hedges → bullish.
• Charm says: as the day passes, those same puts lose delta → dealers reduce short hedges → bullish.

The result is often a persistent, low-drama grind higher with minimal pullbacks. When they diverge, you tend to get choppier, more directionally uncertain sessions.

GEXBoard's regime indicator captures the net effect of all dealer hedging flows, including Vanna and Charm dynamics. A Long Gamma reading during declining IV typically includes a significant Vanna tailwind.