Investing
Options Basics:
What Are Calls and Puts?
Gary Chung（FinKit Editor-in-Chief） · Published：July 23, 2026
Options are one of the most frequently mentioned — yet most misunderstood — financial products in the Hong Kong stock market. You've probably heard people say "buy Call warrants" or "Long Put made several times my money", without fully understanding what they mean. This article starts from zero, using real Tencent and HSBC examples, to help you grasp the basic concepts of Calls and Puts, key terminology, pricing logic, and — most importantly — the real risks of options.
What Is an Option? A Contract of "Rights"
The core definition is simple: An option is a contract giving you the right — but not the obligation — to buy or sell a stock at a pre-agreed price (strike price) on or before a specified date (expiry date).
Analogy: you view a flat listed at HK$8M. You sign a "right of first refusal" contract with the owner, pay HK$100k as a deposit, agreeing that within three months you can buy the flat for HK$8M. If the market price rises to HK$9M after three months, you exercise the right and buy at HK$8M — profit HK$900k (minus HK$100k deposit). If the price falls to HK$7M, you simply walk away — maximum loss is the HK$100k deposit.
This "right of first refusal" is a Call Option. The HK$100k deposit is the Premium, HK$8M is the Strike Price, and three months is the Expiry Date.
📈 Call Option: Betting on a Rise
Buying a Call Option means you're bullish on a stock. You have the right to buy it at the strike price before expiry.
Real Example: Tencent (0700.HK) Call
Suppose Tencent is trading at HK$400 today. You buy:
| Parameter | Value |
|---|---|
| Underlying | Tencent (0700.HK) |
| Strike Price | HK$420 |
| Expiry | 1 month |
| Premium | HK$5/share (1 lot = 100 shares = HK$500) |
| Contract Size | 1 lot = 100 shares |
You pay HK$500 premium for the right to buy 100 Tencent shares at HK$420 within one month. At expiry:
| Share Price at Expiry | Outcome | P&L |
|---|---|---|
| HK$450 (up) | Exercise: buy at $420, market value $450 | Gain: ($450-$420-$5) × 100 = +HK$2,500 |
| HK$425 (slight up) | Exercise: buy at $420, market value $425 | Break-even: ($425-$420-$5) × 100 = HK$0 |
| HK$400 (flat) | Don't exercise ($400 < strike $420) | Loss: Premium HK$500 (100%) |
| HK$380 (down) | Don't exercise | Loss: Premium HK$500 (100%) |
The biggest advantage of buying Calls: loss is capped (maximum = premium paid), upside is unlimited. But the key — the stock must rise above "strike + premium" before you profit. In this example, Tencent must exceed HK$425 to break even.
📉 Put Option: Betting on a Fall
Buying a Put Option means you're bearish on a stock. You have the right to sell it at the strike price before expiry.
Real Example: HSBC (0005.HK) Put
Suppose HSBC is at HK$68. You're worried it'll drop:
| Parameter | Value |
|---|---|
| Underlying | HSBC (0005.HK) |
| Strike Price | HK$65 |
| Expiry | 1 month |
| Premium | HK$1.50/share (1 lot = 400 shares = HK$600) |
| Contract Size | 1 lot = 400 shares |
You pay HK$600 for the right to sell 400 HSBC shares at HK$65 within one month. At expiry:
| Price at Expiry | Outcome | P&L |
|---|---|---|
| HK$60 (down) | Exercise: sell at $65, market $60 | Gain: ($65-$60-$1.50) × 400 = +HK$1,400 |
| HK$63.50 (slight down) | Exercise | Break-even: ($65-$63.50-$1.50) × 400 ≈ HK$0 |
| HK$68 (flat) | Don't exercise ($68 > strike $65) | Loss: Premium HK$600 (100%) |
| HK$75 (up) | Don't exercise | Loss: Premium HK$600 (100%) |
Put logic is the opposite of Call — you profit when the stock falls. Same capped loss (max = premium). Some investors use Puts as a "hedge" — if you hold a lot of HSBC shares, buying Puts can reduce losses during a crash.
Key Options Terminology
| Term | Explanation |
|---|---|
| Strike Price | The pre-agreed price at which you can buy (Call) or sell (Put) |
| Expiry Date | The last valid date of the option contract — expires worthless after |
| Premium | The cost to buy the option; the seller's income |
| In The Money (ITM) | Call: stock price > strike; Put: stock price < strike (has intrinsic value) |
| Out of The Money (OTM) | Call: stock price < strike; Put: stock price > strike (no intrinsic value) |
| At The Money (ATM) | Stock price ≈ strike price |
| Time Value | The closer to expiry, the lower the time value. Zero at expiry. |
| Implied Volatility (IV) | Market's expectation of future price swings. Higher IV = more expensive premiums. |
💡 The Most Common Beginner Mistake
OTM options have very cheap premiums — many think "a few hundred bucks, no big deal if I lose it all." But OTM options have an extremely high probability of expiring worthless — you need a big enough move before expiry to profit. Time value decays daily — even if the stock doesn't drop, your option's value shrinks every day. This phenomenon is called Time Decay, the option buyer's biggest hidden enemy.
What Determines Option Prices? Five Factors
| Factor | Effect on Call | Effect on Put |
|---|---|---|
| ① Stock vs Strike | Higher stock above strike → Call more expensive | Lower stock below strike → Put more expensive |
| ② Time Remaining | More time → more expensive | More time → more expensive |
| ③ Volatility (IV) | Higher IV → more expensive | Higher IV → more expensive |
| ④ Interest Rates | Higher rates → Call slightly pricier | Higher rates → Put slightly cheaper |
| ⑤ Dividends | Dividends → Call slightly cheaper | Dividends → Put slightly pricier |
These five factors form the famous Black-Scholes options pricing model (1997 Nobel Prize in Economics). Retail investors don't need to solve the formula, but should understand the directional impact of each factor.
Options vs Stocks: Key Differences
| Factor | Owning Shares | Buying Options |
|---|---|---|
| Ownership | You're a shareholder with voting + dividend rights | Only contractual rights, not a shareholder |
| Max Loss | Stock falls to $0 (extreme) | Limited to premium (but can be 100%) |
| Leverage | None (unless margin) | Built-in — small capital controls large positions |
| Time Impact | No expiry, can hold forever | Has expiry, time value decays daily |
| Suited For | Long-term investors | Traders with clear directional + timing views |
Options vs Warrants: Don't Confuse Them
Many people confuse options with warrants, but they're fundamentally different. Simplest distinction: options are exchange-standardised products; warrants are packaged products issued by financial institutions.
| Factor | Options | Warrants |
|---|---|---|
| Issuer | Exchange-standardised; anyone can be buyer or seller | Issued by banks/investment banks; you can only be a buyer |
| Counterparty Risk | Clearing house guaranteed, near zero | If issuer collapses, you lose everything |
| Terms | Strike and expiry standardised by exchange | Issuer sets strike, expiry, conversion ratio |
| Liquidity | Market maker system; some stock options trade thin | Issuer quotes prices; you buy/sell through them |
| Roles | Can be buyer or seller (Sell Call/Put to collect premium) | Buyer only; cannot be issuer (cannot Sell to collect premium) |
| Settlement | HK options are American-style (exercisable any trading day before expiry) | Mostly European-style (cash-settled at expiry only) |
| Pricing | Determined by market supply and demand | Issuer-driven — can adjust implied volatility to affect price |
⚠️ Hidden Warrant Risk: Issuer Manipulation
The biggest problem with warrants: the issuer can adjust implied volatility (IV) to affect the warrant price. Suppose you buy a Tencent Call warrant, Tencent's stock rises 5% — theoretically you should profit. But the issuer can simultaneously "narrow IV" — the warrant price may only rise 2%, or even not at all. This isn't illegal; it's part of warrant product design. Options don't have this problem — prices are purely determined by market buyers and sellers, with no middleman able to interfere.
Simple analogy: Options are like shopping at a wet market — you can negotiate with any stall, price is set by the market. Warrants are like buying pre-packaged goods at a supermarket — price and quantity are set by the supermarket, no negotiation.
⚠️ The Real Risks of Options: Three Things Beginners Most Often Miss
1. Time Decay Is the Silent Killer
Even if you get the direction right, if the stock doesn't move enough before expiry, you still lose. Time value decays daily — the last week decays several times faster than the first. Buying an option and watching the stock trade sideways — this is the most common losing scenario.
2. OTM Options Are Like Buying Lottery Tickets
A Call with a strike 30% above the current price may cost only HK$100 in premium. But your probability of winning is below 20%. Long-term OTM option buying is like long-term lottery playing — lots of small losses that add up to a big number.
3. Selling Options (Short Side) Has Unlimited Risk
This article focuses on "buying options" (Long Call / Long Put) — as a buyer, your maximum loss is the premium. But if you sell options (Sell Call / Sell Put), theoretical losses can be unlimited (especially Sell Call). Beginners: do NOT touch the short side until you thoroughly understand the risk in every scenario.
Options Are a Tool, Not a Shortcut
Options themselves are neither good nor bad — they're simply a tool. Calls help you capture upside with less capital; Puts help you hedge downside risk on shares you hold. But options' leverage characteristics make them extremely dangerous: you can make multiples, or lose 100%.
Remember three bottom lines:
- Only use money you're willing to lose 100% of to buy options
- Learn to value the underlying stock first — if you can't judge whether Tencent is worth HK$300 or HK$500, buying Tencent options is pure luck
- Record every trade — 90% of options traders don't know if they're net profitable long-term, because they only remember the wins
Before learning options, use the FinKit Stock Valuation Calculator to learn how to judge a stock's fair value. Valuation is the foundation; options are advanced — don't get the order wrong.
⚠️ Important Risk Disclosure
Options are high-risk derivatives; prices can fluctuate sharply. Buyer maximum loss is limited to the entire premium; sellers may face unlimited losses. Investors should fully understand option mechanics and associated risks, and ensure adequate financial capacity to bear losses. This article is for educational reference only and does not constitute investment advice or solicitation. Consult a licensed professional advisor if in doubt.