How Many Open Positions Can Your Book Actually Carry?

There is no right number of open option positions for a book your size, and every answer that hands you one is guessing. The ceiling on my own book is not a count at all — it is a headroom calculation, and last Friday it said twelve positions were fine in one configuration and a breach in another. Same twelve. The number that governs you is the point where the assignment you should expect exceeds the room your own allocation policy leaves for it.

How many option positions should you have open?

Ask that question anywhere traders gather and you will be handed a number within a minute. Three to eight. Five to seven. Twenty to twenty-five. Under forty. Every one of those is somebody's real experience honestly reported, and not one of them comes with a derivation you could run on your own book. They are personal tolerances wearing the costume of a rule.

I ran a book that way for years, and the number I would have given you drifted with my mood. What replaced it was duller: a written ceiling, checked every Friday on the same basis, that does not care how confident I feel. The arithmetic is not complicated. The reason nobody publishes it as an answer is that it returns a different one for every book — useless as a headline, useful as a rule.

A count is something you can report. A ceiling is something you can breach. Only one of those governs anything.

Why the count is the wrong unit

Start with what a short put is actually promising. When you sell one you are not taking a position with a size; you are accepting an obligation with a probability attached. FINRA puts the obligation plainly: the seller “accepts the obligation to buy or sell the underlying asset if the contract is assigned”, and for equity options, “assignment can happen at any time” (FINRA, Options). And the same page states the size of it without flinching: for the writer of an uncovered put, “the maximum loss … is the strike price of the put”. Assignment on a short put becomes likelier as time value decays and as the strike moves deep into the money near expiry — not, as is often repeated, around a dividend, which is a reason to exercise a call early, not a put.

Hold both of those in view, because everything below discounts that maximum by how often assignment actually happens, and a discounted number is not a smaller obligation. Your upside on a short put is the premium and nothing more. Your downside is the strike less the premium, per contract, and on a margin account it is financed.

That is why a count cannot carry the weight people put on it. Twelve puts on twelve-thousand-dollar strikes and twelve on forty-thousand-dollar strikes are the same number and nothing like the same promise; two puts of identical size written under different strategies carry different odds of becoming stock. The count is blind to size and blind to odds. How much that hurts depends on where the stock trades when it lands, which nothing here measures — this sizes the position you can absorb, not the loss.

The library already has the single-position half of this problem: sizing one holding against net asset value is the largest-position discipline, and whether a long list of names is really diversified is its own question. Neither asks how many obligations the book can carry at once, which is the question a weekly income engine actually runs into first.

What actually sets your ceiling

Here is the whole model in one line. Your allocation policy already gives each strategy a cap — a share of total assets it is allowed to grow into. Total assets here means the gross market value of what you hold, and that choice has a consequence worth saying out loud: borrowing more raises the cap, raises the headroom, and permits more writing. A rule that loosens as leverage rises deserves suspicion. What bounds it is that margin is governed separately and outranks this test — and if you would rather the cap not expand with the loan, set it against net equity, where it binds harder. Some of that cap is already spent on stock you were assigned earlier and still hold. What is left is your headroom. Capacity is breached when the assignment you should expect from everything currently open is larger than that headroom.

Three quantities, and every one of them is on your own statement or in your own policy:

Say plainly what that test is and is not. It sizes how much stock can land on you in an ordinary week. It is not a cap on a bad one: Book A below expects $4,200 of assignment against $9,200 of headroom, and the most it can be handed is the full $168,000 — eighteen times that headroom. Short-put assignments are not independent, either. A broad drawdown puts everything in the money at once, which is exactly the week a rate measured on ordinary weeks stops describing anything. Read the full notional beside the expected figure and treat that as the real test.

An expected value describes an ordinary week. The strike describes the other kind, and only one of them is a promise you signed.

Notice what the model does not contain. There is no view on whether the market is expensive, no forecast, and no opinion about which strikes to write. It is a containment rule: it asks whether the stock you would be handed, if the odds behaved normally, still fits inside the space your own policy set aside for it. Capacity is dynamic by design — as the book grows the cap grows with it, and as assigned stock is sold the headroom comes back.

Twelve positions, three books, two verdicts

A worked case, on a book shaped like mine but not it. Gross securities value $1,360,000, against a margin loan of $394,400. Utilization is the loan divided by the gross securities value — the market value of everything held, before the loan is netted, with no cash term — which puts this book at 29.00%, inside Clear — and that boundary only means what it says against that denominator. The same loan measured against net equity, which is how leverage is more commonly quoted, reads 40.85%, over the line this same system calls Forced. If you use a different denominator these boundaries do not travel with you; recalibrate them, or you will read the opposite verdict off the identical book. It stays at 29.00% in all three versions below, because none of them changes the loan or the book.

One thing that ratio does not see, and I would rather name it than have it found: uncovered puts carry a margin requirement of their own, and it differs across these three books. On the exchange minimum alone — a floor of ten per cent of aggregate exercise price — Book B demands roughly $24,000 more than A or C. They are equivalent on this ratio and not equivalent in buying power, which is what decides whether a broker liquidates you. That is the same blindness this post accuses a position count of, sitting in my own denominator.

Two strategies write short puts here — uncovered, on margin, not cash-secured: a book already carrying a $394,400 loan is not simultaneously setting $408,000 aside. Constant Cashflow is the weekly line, Weekend Windfall the short-dated one. Each has an allocation target of 4.5% of total assets, so a cap of $61,200. Each is already holding $52,000 of stock it was assigned earlier, leaving $9,200 of headroom apiece. Every version below has exactly twelve open short puts.

Twelve open puts	Open notional	Expected assignment	Headroom	Verdict
A — twelve Constant Cashflow puts at $14,000	$168,000	$4,200	$9,200	Inside
B — twelve Constant Cashflow puts at $34,000	$408,000	$10,200	$9,200	Breach
C — eight Constant Cashflow and four Weekend Windfall, all at $14,000	$168,000	$2,800 · $11,200	$9,200 · $9,200	Breach

Book B is the easy one: same twelve positions, bigger each, and the expected assignment of $10,200 overruns $9,200 of headroom. Anyone who counts positions and stops there records B and A as identical books.

Book C is the one worth sitting with. It has the same twelve positions as A and the same $168,000 of open notional. Every input a position count could see is identical. Four of the twelve are simply written under the other strategy — and that strategy's four puts, $56,000 of notional, produce an expected assignment of $11,200 against the same $9,200 of headroom. C breaches on $56,000 of notional — a seventh of what B needed to break the same rule. Book A and Book C differ in nothing a count can measure, and they land on opposite verdicts.

Twelve positions was never the fact. What the twelve were made of was the fact, and the count is the one number that cannot see it.

Why one assignment rate cannot cover both strategies

The thing separating Book A from Book C is a rate, and rates are the part of this you cannot borrow from anyone else. Over a rolling year of my own closed trades, matched option by option against what the broker actually did with them, my two put-writing strategies did not behave remotely alike: the weekly line was assigned five times in three hundred and sixteen events, the short-dated one six times in thirty-one. That is roughly 1.6% against 19.4%. I govern them at 2.5% and 20%.

Be precise about what I did to get there, because “rounded up” would flatter it. The low one I raised by about half again, from 1.58% to 2.5%; the high one I barely moved, from 19.35% to 20%. The cushions are not equal, and the reason is sample size rather than prudence — I trust three hundred events more than I trust thirty-one, so the thin one gets no credit for looking precise.

Those numbers are mine, and the point of publishing them is not their level: it is that two strategies I run on the same book, in the same account, came out more than an order of magnitude apart on the one input that decides capacity. No single blended rate could have governed both. The rates I actually run sit eight times apart — narrower than what I measured, because of that uneven cushion.

Do not copy either one, and understand how soft the second is. Six events in thirty-one is a thin sample: with ordinary statistical confidence the true rate sits somewhere between about 9% and 36%, and at the top of that range Book C's Weekend Windfall leg would expect not $11,200 of assignment but better than $20,000 — a breach more than twice as deep as the one in the table. The uncertainty is in the first digit, not the second decimal. And there is a limit I cannot measure away: one year is one regime, and a rate measured over a period without a deep drawdown is not the rate that applies in the week your headroom is finally tested.

A rule that loosens as leverage rises deserves suspicion — including, and especially, when the rule is your own.

What travels is the discipline, not the figures: measure your own, per strategy, and write the event count down beside every rate so you can see how thin it is.

One boundary worth stating plainly, because it is where people over-extend the model: none of this describes index spreads. A European-style, cash-settled index spread cannot be assigned into stock at all — its worst case really is fixed when you open it, and it belongs in a separate bucket governed by total defined loss rather than by expected assignment. Be careful extending that to an equity vertical, which is a different animal: its short leg is American-style and can be assigned early, and the loss stays defined only while you still hold the long leg and exercise it against the assignment. Neither belongs in the test above; only one of them is genuinely immune to the problem the test exists for.

What a capacity breach actually tells you to do

A breach is not a signal to close anything. The instruction it produces is narrow and deliberately dull: pause new short put writing in the breached strategy until capacity clears. You keep what is open. You let it expire, or you are assigned and the Layer — my word for one strategy inside the book — absorbs it. What you stop doing is adding a new obligation to a Layer that has already promised more than its policy leaves room for.

Two details about the timing matter, and they cut in opposite directions. First, a label: the four margin zones I keep naming — Clear, Harvest, Freeze, Forced — and the waiting period below are my house rules, not regulation, and deliberately far more conservative than any broker trigger. Read them as an example of having written rules at all, not as the rules you must adopt. Most breaches under them have to prove they are real before they drive anything — the rule is that a breach must persist across two consecutive weekly snapshots, because one bad Friday is noise and two is a condition. A capacity breach is not one of those: it applies from the first reading. The reason is that it takes nothing away and commits nothing — it only stops you adding risk, which is the same shape as a standing “no new positions” constraint rather than an action. The other first-reading rule among the margin zones is Forced, at 40% utilization and above, and that one is an action; if you are listing the rules that skip the waiting period, those are the two.

When several things breach at once, order them by what can end the operation. Margin first, always — a margin problem is existential in a way a capacity problem is not. Then allocation. Capacity after both. My own scoring reflects that ordering rather than proving it: margin carries the most weight and a Forced reading caps the score outright, while a capacity breach does not. The argument for the order is the first sentence here, and it stands without the scoring. In Book B and Book C the margin reading is 29.00% and Clear, so capacity is the only thing on the list; on a week where utilization had also climbed, the reduction would be read first and the put pause would still be sitting underneath it, unchanged.

A rule that only stops you adding risk does not need a week to prove itself. A rule that takes something away does.

Both of those rules live in a policy file rather than in the engine's code, which is the part that makes them yours to change. The wider argument for keeping thresholds outside the thing that enforces them is the governance layer itself. And when one of these puts does resolve, book the premium when it is actually realised — not when you sold it.

Run the capacity check on your own book

Fifteen minutes, once, and then a few minutes every Friday. Take each put-writing strategy separately — the whole model collapses if you pool them, which is the mistake Book C is built to expose.

Multiply that strategy's allowed share by your total assets to get the cap. Subtract the market value of stock it has already been assigned and still holds; what remains is the headroom. Add up the notional of every open short put in it — strike times a hundred times contracts — and multiply by your own measured assignment rate. If you have not measured one, do not pick a number you like: the rate is the only real input here, and anyone who wants to keep writing puts will choose 2% and find every book comfortably inside. Until you have a genuine sample use a rate high enough to be uncomfortable — I would not go below 20% on anything short-dated — and treat the answer as provisional. If that product is larger than the headroom, you are over capacity, and the instruction is to stop writing new puts there until it is not.

Then write the ceiling somewhere that outlives the week you set it — which is what the Investment Charter, the written statement of what the money is for and the limits on how it gets there, exists to hold. A ceiling you keep only in your head is a mood, and it will move on the Friday you least want it to.

The part that takes the fifteen minutes is the rate, and it is the part worth doing properly: pull a year of closed trades, tag them by strategy, and count how many ended in assignment rather than expiry. If the answer is that you have no idea, that is the finding. You have been sizing an obligation by how many of them there are.

Frequently asked questions

How many option positions is too many?

There is no universal number; one offered without a derivation is somebody's tolerance. The ceiling is the point where expected assignment — your measured assignment rate times the notional currently open — exceeds the headroom left in that strategy's allocation cap. Two books with the same count can sit on opposite sides of it. But expected assignment describes an ordinary week: the most you can be handed is the full notional, and a market-wide drawdown assigns everything at once.

What is options capacity?

Capacity is the room a put-writing strategy has left to absorb being assigned. Its cap is the share of total assets your allocation policy gives that strategy; headroom is the cap minus the assigned stock it already holds. Capacity is breached when the assignment you should expect from what is open exceeds that headroom. It is measured per strategy, never pooled across the book.

Does a capacity breach mean I should close positions?

No. The instruction is to pause writing new short puts in the breached strategy until capacity clears. Existing positions are left to expire or be assigned. Unlike most breaches in this system, which must persist across two consecutive weekly readings before they drive anything, the capacity pause applies from the first reading — because it adds no trade and only stops you taking on more obligation.

How do I work out my own assignment rate?

Pull a year of closed option trades, tag each by the strategy that wrote it, and count how many ended in assignment rather than expiry. Do it per strategy: mine measured roughly 1.6% and 19.4%, more than an order of magnitude apart, so a blended rate would have flattered one and punished the other. Write the event counts beside the rates — six assignments in thirty-one events is a far weaker number than 19.4% looks. Round the result upward so the cushion errs against you, and recalibrate on a schedule rather than after a result you did not like.

Does this apply to spreads and condors?

Not to European-style, cash-settled index spreads — those cannot be assigned into stock at all, and are governed separately by total defined loss against the size of the book. An equity vertical is not in the same position: its short leg can be assigned early, and the loss is only defined while the long leg is still there to be exercised against it. The capacity test here is for uncovered short puts that can turn into stock you must hold and finance.

Incomestead recommends. You decide.