Strike Price Explained: How It Impacts Options Trading in Australia (2025 Guide)

If you’ve ever been curious about options trading in Australia, you’ve likely come across the term strike price. It’s not just industry jargon—it’s the backbone of every options contract and a critical factor in your potential profits (or losses). With the ASX seeing a surge in retail options trading and 2025 bringing new rules for derivatives, understanding strike prices has never been more important for savvy investors.

What Exactly Is a Strike Price?

The strike price (sometimes called the exercise price) is the fixed price at which the holder of an options contract can buy (call option) or sell (put option) the underlying asset. When you buy an option, you’re essentially locking in the right to transact at this predetermined price, regardless of where the market moves.

• Call Option: The right to buy at the strike price.
• Put Option: The right to sell at the strike price.

For example, if you purchase a call option for BHP shares with a strike price of $45, you have the right to buy those shares at $45—even if the market price jumps to $55 before expiry.

Why Strike Price Matters in 2025

The importance of strike price isn’t static—it evolves with market trends and regulatory updates. In 2025, the ASX has updated its margin requirements and expanded the available strike price intervals for popular stocks and ETFs, giving investors more flexibility but also demanding sharper decision-making.

• New Strike Price Intervals: For high-volume stocks, strike prices may be available in $0.50 increments rather than $1, allowing finer-tuned strategies.
• Impact on Premiums: The strike price is a major determinant of the option’s premium (the price you pay to buy the option). Options with strike prices far from the current market price are cheaper but less likely to become profitable.
• Tax Implications: 2025 ATO updates clarify how capital gains tax is calculated on options exercised at the strike price, which can influence your after-tax returns.

These changes underscore the need to match your strike price choices with your risk tolerance and market outlook.

Real-World Strategies: Choosing the Right Strike Price

Picking the right strike price isn’t just about guessing where a stock might go—it’s about aligning with your investment goals. Here’s how different strategies use strike prices:

• In-the-Money (ITM): The strike price is below the current market price (for calls) or above it (for puts). These cost more but have intrinsic value.
• At-the-Money (ATM): The strike price is close to the current market price. These are popular for short-term traders betting on sharp moves.
• Out-of-the-Money (OTM): The strike price is above (call) or below (put) the current price. These are cheaper, high-risk, high-reward bets.

Let’s look at an example:

• Scenario: CSL shares are trading at $300. You’re bullish and consider buying a call option.
• ITM: Strike price $295 (higher premium, more likely to profit if CSL rises).
• ATM: Strike price $300 (balanced cost, needs a decent move to profit).
• OTM: Strike price $310 (cheap, but CSL must rally hard to make money).

In 2025, ASX’s more granular strike offerings mean you can fine-tune your approach, whether you’re hedging a portfolio or taking a speculative punt.

Strike Price Pitfalls and Pro Tips

Even experienced traders can trip up with strike prices. Here are common mistakes and how to avoid them:

• Ignoring Volatility: High volatility can make distant OTM options more expensive than you expect.
• Forgetting Expiry: The closer you get to expiry, the more the strike price’s relationship to the current market price matters.
• Overlooking Liquidity: Unpopular strike prices can be harder to trade out of, especially in fast-moving markets.

Pro Tip: Use the ASX’s updated options calculator to model outcomes with different strike prices before committing capital.