A cash-secured put is a promise with money behind it. You agree to buy 100 shares at a price you name, you set aside the cash to honour that promise, and you are paid a premium for making it. If the stock stays above your price, you keep the premium and the promise expires. If it does not, you buy the shares — at the price you chose, which is the whole point.

It is the most misunderstood beginner strategy in options, usually because it gets sold as “free money” and the assignment case is treated as an accident rather than as half the design. Build one below and look at both halves.

The four numbers that define the trade

Capital committed. The cash you must set aside is the strike times 100 times the number of contracts. A $95 put requires $9,500 per contract, parked and unavailable. This is the real constraint on the strategy — not risk appetite, but how many $9,500 blocks your account contains.

Breakeven. The strike less the premium collected. Above it you are ahead; below it you are behind. Note that this sits below the strike, which means the stock can fall somewhat and you still make money.

Return on capital. Premium divided by capital committed. This is the honest per-cycle figure, and it is usually humbling — a respectable CSP earns something like 0.8% to 2% over a month.

Annualised return. That per-cycle return scaled to a year. It makes trades of different lengths comparable, and it is the number most likely to mislead you. More on that below.

Three ways it ends

The top three rows are the same outcome. That is the structural advantage: the stock can rise, stall, or fall by up to 5% and every one of those pays identically. You are not betting on direction, you are betting against a specific magnitude of decline.

The annualised number, and how to read it

Premium Tracker and this widget both compute annualised return the same way:

A $185 credit on $9,500 over 30 days is 1.95% per cycle and about 23.7% annualised. That second figure is genuinely useful for comparing a 30-day trade against a 45-day one. It is genuinely misleading if you read it as a return you will earn.

Three reasons it overstates reality. It assumes you find an equally good trade the moment this one closes, twelve times a year. It assumes every cycle expires worthless — losing cycles are not in the number. And it ignores the days your capital sits idle between positions. Treat it as a comparison unit, like a price per litre, not as a projection.

Choosing the strike

The strike is the only meaningful decision, and it is a trade-off with no correct answer. Closer to the money pays more and gets assigned more. Further out pays less and is assigned less. The strike selection lesson compares four delta targets side by side with real numbers.

The filter that matters more than delta: would you be content owning 100 shares of this company at this strike, and can you afford to? If the answer to either half is no, no premium makes the trade sound. This is the discipline that separates a cash-secured put from a leveraged bet with a reassuring name.

What can go wrong

Selling on a stock you do not want. The strategy’s plan for its own bad case is ownership. Remove that and there is no plan.

Not actually securing the cash. A broker may let you sell the put on margin. The payoff looks identical right up until assignment arrives with a margin call attached.

Chasing high premiums. Unusually rich premium is the market pricing unusually high risk — often an earnings date or pending news. The premium is not a bargain; it is a quote for a risk you may not have noticed.

Concentrating in one name. Five CSPs on one ticker is one position wearing a disguise. In a real decline they all get assigned together.

Ignoring the drag of fees. On a $185 credit, a couple of dollars of commission plus a wide spread can take 5% of the trade’s income before it starts.