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Buy to close or let it expire? Pennies now vs the last-day risk

Letting a cheap short option expire saves you a few cents. Buying it back costs a few cents and ends the risk. Most of the time expiring wins. When it loses, it loses big.

Comparison · 6-minute read · Updated 2026-10-26

The short answer

Buy to close means you pay to buy back the option you sold. The trade is over. You keep the premium minus what you paid. See Buy to close.

Letting it expire means you do nothing. If the option ends out of the money, it disappears and you keep the full premium. If it ends in the money, even by a little, you get Assignment.

So the choice is simple. Pay a small, known cost now. Or save that cost and keep the risk until the final bell.

Side by side

A worked example (an illustration, not a trade idea)

A made-up stock, XYZ, trades at $50. You sell a 30-day $45 put for $1.00. You collect $100. Your broker sets aside $4,500.

It goes well. With two days left, XYZ sits at $49. The put is now worth $0.05. Buying it back costs $5, plus a commission.

You think: "Why pay $5? It's going to expire." So you hold.

On the last day, XYZ reports bad news before the open. It falls to $42 and stays there.

Look at what the $5 bought. In the good case, holding earned $5 more. In the bad case, it cost $295 more than closing, and you now own 100 shares you may not want at $45.

That's the trade you make by letting a cheap option ride. You risk hundreds to save a few dollars.

Why the last day is riskier than it looks

Three things can go wrong in the final hours:

1. News. Earnings, a downgrade or a market drop can move the stock past your strike in one day.
2. Pin risk. If the stock closes right at your strike, you can't be sure whether you'll be assigned.
3. After-hours moves. Trading in the stock goes on after the 4 p.m. close. Option holders can still decide to exercise for a short window after that. A late move can turn an option you thought was dead into an assignment.

None of these is likely on any single trade. Over many trades, one of them will happen to you.

Which one fits this trade?

When letting it expire is fine

Doing nothing is a real choice. It makes sense when:

• The strike is far from the price, and expiry is hours away, not days.
• No earnings or big news falls before expiry.
• You'd be glad to own the shares (put) or sell them (call) at the strike anyway.
• The buyback cost is close to the commission. Paying $0.65 to save $1 is silly.

In the wheel strategy, assignment is part of the plan. If you'd happily own XYZ at $45, letting the put expire is less scary. You still don't want to own it at $45 when it trades at $35.

When buying to close is the better move

• Most of the premium is gone and days are left. You've kept most of what you can earn. The rest isn't worth the risk.
• Earnings or an ex-dividend date is coming. See Ex-dividend date.
• You want the cash or shares back. Closing frees them for the next trade.
• The stock is creeping toward the strike. Closing early is cheaper than closing after it crosses.

Many sellers place a standing order to buy back at a low price, such as $0.05. If the option touches it, the trade ends on its own. Use a limit order; never a market order on a thin option.

What to do with this

1. Before you sell, decide your buyback price and write it down.
2. With two or three days left, check: is there news before expiry? How close is the stock to the strike?
3. Ask, "Would I take this risk for this much premium today?" If the answer is no, buy it back.

The same idea shows up in closing early vs rolling and in our theta decay guide.

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