Bollinger Band + cash-secured put (BB + CSP)

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A cash-secured put pays you a premium for agreeing to buy 100 shares at the strike — but when you sell matters. This lesson adds a rules-based timer: sell the CSP when the daily price touches the lower Bollinger Band.

The logic is simple. A lower-band touch means price sits about two standard deviations below its 20-day average — statistically stretched. Selloffs like that usually arrive with elevated implied volatility (IV), and high IV means richer put premiums. You sell expensive insurance after a dip, with a strike set well below, and let time decay do the work.

Bollinger Bands in 30 seconds

• Middle line: the 20-day simple moving average of price
• Upper / lower bands: the middle ± 2 standard deviations
• Lower-band touch: price roughly 2σ below its average — short-term oversold relative to its own recent history

Honest framing first: bands describe where price has been, not where it is going. A touch is a disciplined entry trigger, not a prediction. The edge in this strategy comes from the CSP mechanics — elevated IV, far out-of-the-money strikes, daily theta decay — and the bands simply keep your timing consistent instead of emotional.

The rules

1. Market regime: neutral or bullish only

This strategy does not fight downtrends. Skip the trade when the weekly or daily trend is clearly down — price under a falling 50-day moving average, or a pattern of lower highs and lower lows. In a real downtrend, price can ride the lower band for weeks: every touch is a falling knife, not a bargain.

2. Entry: daily touch of the lower band

When the daily candle touches or closes below the lower Bollinger Band (20, 2), that is your signal to evaluate a CSP — not before. No touch, no trade.

3. The put: 45+ DTE, about 10% below spot

• Expiry: 45 days or more — the theta-decay sweet spot: enough premium to matter, enough time for price to stabilize
• Strike: roughly 10% below the current spot — or about 10 delta, whichever fits the ticker better. On very volatile names 10% can still be near the money, so let delta be the tiebreaker.
• Only sell on underlyings you would be happy to own at the strike — the golden rule of CSPs applies double here.

4. Exits — whichever comes first

• 50% of max profit: close once you have kept half the premium. This locks in most of the gain and frees your cash for the next setup.
• 21 DTE: close with three weeks left, no matter what. Gamma risk accelerates inside ~21 days — this rule sidesteps expiry-week drama.
• Upper-band touch: if price rallies to the upper Bollinger Band, the mean-reversion move you were paid to wait for has happened — take the win.

What it looks like on a real chart

The charts below show the setup's shape on SPY — they illustrate the pattern, they don't predict future results.

Why these numbers work

• 45 DTE: theta decay is strong, yet there is time for the snap-back
• 21 DTE: gamma — the risk of violent price moves near expiry — rises sharply, so the rule exits before it
• 50%: most CSPs reach half-profit well before expiry; waiting for the last dollar ties up capital
• Upper band: a symmetric exit — you entered on stretched weakness, you leave on stretched strength

Where the edge really comes from

Be clear-eyed: the Bollinger touch itself predicts nothing — band touches have weak standalone forecasting power. The returns here come from three structural facts: (1) you sell when IV is elevated, (2) far out-of-the-money puts expire worthless most of the time, (3) every passing day melts the put's time value in your favor. The bands are the discipline layer — a repeatable trigger that stops you from selling puts at random emotional moments.

Pairs with the Wheel

Assignment isn't a failure of this strategy — it's the Wheel's first step. If the put is assigned, you own 100 shares at the strike (minus the premium you kept). The Wheel continues from there: sell covered calls against the shares until they are called away, then restart the cycle with a fresh Bollinger-timed CSP.

Try it in the Builder

Open Cash-Secured Put in Builder → CSP basics Advanced lessons

Model it: short put, about 45 DTE, strike ~10% below spot. Check max profit, break-even and probability of profit — then move the strike closer and watch how the numbers change.

Beginner FAQ

Why 45 DTE instead of 30?
45 DTE holds more premium and gives the mean-reversion room to play out. 30 DTE decays faster but pays less and forgives less if the recovery is slow.

What if the stock keeps falling after I sell?
Then assignment is the outcome: you buy 100 shares at the strike. This is why the regime filter and the "happy to own it" rule are non-negotiable.

Can I use this on any stock?
It works best on liquid underlyings with tight bid-ask spreads. On very volatile names, 10% below spot can still be close to the money — use about 10 delta instead of a fixed 10%.

Does the upper-band exit leave money on the table?
Sometimes, when momentum continues after the touch. The rule deliberately trades the last dollars for consistency.

Next: Compare with the plain cash-secured put, then test both in the Strategy Builder.