Short put vs bull put spread: full collateral, or a capped loss?
A short put is one contract backed by cash for 100 shares. A bull put spread is that same short put plus a cheaper long put below it, which caps the loss. One is the wheel's first step. The other is a capped bet.
The short answer
A short put, when backed by cash, is a Cash-secured put. You sell a Put option, set aside the strike × 100 in cash, and agree to buy the shares if asked. Max loss: the strike minus the premium, times 100.
A bull put spread is the same short put plus a long put at a lower strike. The long put caps the loss at the distance between the strikes, minus the premium. You collect less, you tie up far less cash, and you do not want the shares.
If the point is to own the stock at a discount, the short put. If the point is a capped bet that the stock stays up, the spread.
Side by side
| Short put (cash-secured) | Bull put spread | |
|---|---|---|
| Legs | One | Two |
| Premium | Full | Less; the long put costs some of it |
| Cash tied up | Strike × 100 | Width of the spread × 100, minus the credit |
| Max loss | Strike − premium, × 100 | (Width − credit) × 100 |
| Max gain | The premium | The net credit |
| Assignment | Shares arrive; you have the cash | Shares can arrive on the short leg with no cash set aside |
| Fees and spreads | One leg | Two legs, open and close |
| Approval level | Basic to mid, depends on broker | Usually a level up; needs spread approval |
| Fits the wheel | Yes | No |
A worked example (an illustration, not a trade idea)
XYZ trades at $50, 30 days out.
- Short put: sell the $45 put for $1.00. Collect $100. Cash set aside: $4,500.
- Bull put spread: sell the $45 put for $1.00, buy the $40 put for $0.40. Net credit $0.60, $60. Cash set aside: $500 ($5 width × 100), with the $60 credit against it. Max loss: $440.
| XYZ at expiry | Short put | Bull put spread |
|---|---|---|
| $55 | +$100 | +$60 |
| $45 | +$100, or you own 100 shares at $45 | +$60 |
| $43 | Own shares at $45, worth $43: −$200 + $100 = −$100 | Short leg loses $200, long leg worthless: −$200 + $60 = −$140 |
| $38 | Own shares at $45, worth $38: −$700 + $100 = −$600, shares in hand | −$500 + $60 = −$440, max loss, nothing in hand |
| $25 | −$2,000 + $100 = −$1,900 | −$440 |
Three things the table shows.
- Small dips hurt the spread slightly more. At $43 the spread lost $140, the short put $100. The long put cost premium and did nothing.
- Big drops are where the spread earns its keep. At $25 the short put is down $1,900 and holding a broken stock. The spread stopped at $440.
- The spread's loss is big against its collateral. $440 lost on $500 set aside is most of it. The short put's $600 at $38 is a smaller share of $4,500. "Defined risk" defines the dollars, not the percentage.
The Friday-between-the-strikes trap
At $43 in the table, the short $45 put is in the money and the long $40 put is not. If you hold to expiry, the short leg is assigned: 100 shares at $45, $4,500 taken from an account that only set aside $500. The long put expires worthless and protects nothing.
Many brokers will close or margin-call that on Monday, at Monday's price. This is the main way a "capped" trade turns into an uncapped one. Close spreads before expiry when the stock sits near the short strike. See single-leg vs multi-leg options.
Why the wheel uses the short put
The wheel strategy wants to own the shares if the stock dips. The cash is set aside on purpose; assignment is step two, not a failure. The spread throws that away: it gives up the shares and most of the premium to buy a floor.
A seller who finds themselves wanting the spread's floor on a stock should ask why. If the honest answer is "I don't want to own this stock", the fix is a different stock, not a second leg.
Which one fits you?
- Would buy 100 shares at the strike and can set aside the cash: the short put. See the cash-secured put guide for every outcome.
- Cannot set aside the cash, or do not want the stock: the spread, sized so the max loss is one you can take, and closed before expiry.
- Want "the premium of a short put with the risk of a spread": that does not exist. Lower premium is the price of the cap.
One line for Canadian readers: cash-secured puts are allowed in a TFSA or RRSP at some brokers and not others, and the same goes for spreads. Options permissions differ by broker.
Questions
Is a bull put spread less risky than a cash-secured put?
Its worst case is a smaller dollar number, capped by the long put. But a small dip costs it a bit more, the cap only holds if you close before assignment, and the loss is a large share of the cash tied up.
Can a bull put spread be assigned?
Yes, on the short leg. If the stock ends between the strikes at expiry, you can be assigned 100 shares with no cash set aside for them. Close the spread before expiry if the stock is near the short strike.
Why does a short put collect more premium than a spread?
The spread's long put costs money. Its price is subtracted from the short put's premium. You are buying a floor, and the floor is not free.
Can I turn a cash-secured put into a spread later?
Yes, by buying a lower put while the short one is open. It costs the long put's premium at that moment, which is high if the stock has already fallen. Deciding the structure before you sell is cheaper.
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