Five things to learn first, in this order: (1) what an option actually is, (2) calls vs puts, (3) delta (the only Greek that matters at first), (4) how time decay (theta) works, (5) the cash-secured put — your first premium-selling trade. Move on to the Level 2 strategies or the Greeks pages only after these five are second nature. Most UK retail losses come from skipping ahead.
1. What an option actually is
An option is a contract that gives you the right but not the obligation to buy or sell something at a specific price (the strike) by a specific date (expiration). You pay a premium to the seller for that right.
Key analogy: think of a deposit on a house. You pay £1,000 for the option to buy the house at £300,000 within 30 days. If house prices spike to £350,000, you exercise (buy at £300,000 and sell at £350,000 — £49,000 profit). If house prices fall to £280,000, you walk away — you lose only the £1,000 deposit. Options work the same way on shares.
One US-listed contract covers 100 shares, so a $1.50 call premium costs $150 per contract. A traditional ICE UK single-stock contract covers 1,000 shares and is quoted in pence, so a 15p premium costs £150; ICE also lists newer 100-share series on some names, and a FTSE 100 index option is £10 per point. Read the contract size off the chain and multiply by it before you place any order.
2. Calls vs puts
- Call option: right to BUY the underlying at the strike. Bullish bet (you profit if the stock rises).
- Put option: right to SELL the underlying at the strike. Bearish bet (you profit if the stock falls) OR insurance on shares you own.
For every option there's a buyer and a seller. The buyer pays premium for the right. The seller (writer) collects premium and takes on the obligation. As a beginner, never sell an option you have not fully covered: an uncovered short call has unlimited risk and an uncovered short put risks the whole strike. Buying options, and selling ones that are fully cash-secured or covered by shares you hold, is Level 1 territory; everything else waits until you have cleared that gate.
3. Delta — the only Greek that matters at first
Delta is how much the option price moves for each £1 move in the underlying.
- Delta of 0.50 = option moves 50p for every £1 the stock moves.
- At-the-money options (strike near current price) have delta around 0.50.
- Deep in-the-money calls have delta near 1.00 (move like the stock itself).
- Deep out-of-the-money calls have delta near 0.00 (almost no movement).
Delta is also a rough proxy for "probability of finishing in the money" — a 0.30 delta call has roughly a 30% chance of finishing profitable. Useful mental model.
Other Greeks (gamma, theta, vega, rho) matter eventually. For your first 10 trades, just track delta.
4. How time decay (theta) works
An option is wasting asset — it loses value as expiration approaches, even if the underlying doesn't move. This is "theta decay."
- A 30-day option loses very little value day 1. It loses dramatic value in the final week.
- Theta is the amount, in pence or dollars per share, the option loses per day. A theta of −0.05 = the option loses 5p of value per day.
- Short-dated options (7-14 days) have the highest theta — fastest decay.
- Long-dated options (3+ months) have low theta — slow decay.
For beginners, this means: don't buy options that expire in 1-7 days unless you're sure of the move. The decay will kill you. Stick to 30-60 day expirations until you understand IV crush.
5. The cash-secured put — your first premium-selling trade
The cash-secured put is the usual Level 1 starting point for selling premium, once a long call and a long put have shown you how an option behaves. Mechanics:
- Choose a high-quality stock you'd be happy to OWN at a discount.
- Sell a put option at a strike BELOW the current price (typically 5-10% below).
- You collect a premium upfront.
- You hold the cash needed to buy at the strike (that's why it's "cash-secured").
Three outcomes:
- Stock stays above the strike at expiration: the put expires worthless. You keep the full premium. Repeat next month.
- Stock finishes a little below the strike: you're assigned the shares (you buy them at the strike). Your effective purchase price is the strike minus the premium received, and you own a company you chose at a price you chose.
- Stock falls a long way below the strike: you are still assigned at the strike, and you now hold shares worth far less than you paid. The premium does not protect you from this. Your maximum loss is the strike times the contract size, less the premium: on a 1,000-share ICE contract at 430p that is £4,300 less the premium if the company fails.
The first two outcomes are what the strategy is designed for. The third is what it costs, and it is why the put is sold only on a share you would hold unhedged through a bad year, at a size where the third outcome is survivable. Cash-secured puts on quality companies are the starting point of most retail premium-selling, not because they are safe but because the worst case is a number you can write down first.
Common beginner mistakes
- Buying 7-day OTM options. Theta destroys these. Most lose 100% of their premium.
- Selling naked calls. Theoretical maximum loss is unlimited. Don't.
- Trading earnings. Implied volatility crushes after earnings — even if your directional bet was right, you can lose money. See the earnings + IV crush guide.
- Trading meme stocks. The implied volatility is gambling-grade. Stick to large-cap quality (£10bn+ market cap) for your first 6 months.
- Position-sizing too large. The library's sizing rule is 1-2-5: 1% of the portfolio on a speculative trade, 2% on a directional one, and up to 5% only on defined-risk income; more than that on a single options trade is portfolio-killing. See position sizing guide.
What to read next
One path, in order. Each step gates the next.
- UK basics — contract sizes, exercise style, settlement and the approval process, with the contract-standards table.
- Assignment and expiry — what happens to a short option you do not close, before you ever sell one.
- Level 1 — Foundation — the five fully covered structures in the order to trade them: long call, long put, cash-secured put, covered call, collar.
- Greeks and implied volatility — when you are ready for gamma, vega and IV rank, which the Level 2 gate requires.
- UK tax and platforms and the tax worked examples — the record-keeping every trade above creates.
Sources and methodology
This page is educational only and not financial advice. Options carry the risk of losing your entire premium and (when selling) potentially unlimited loss. The full UK Tax Drag options reference is in the options trading guide. For regulated investment advice, consult an FCA-authorised IFA — see the tax adviser editorial recommendation. The methodology page documents sources.
Related options guides
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