When it comes to buying and selling shares, bonds, or ETFs on the Australian Securities Exchange (ASX) or global markets, understanding the concept of a ‘lot’ can make a significant difference to your trading strategy and costs. In 2025, as more Australians explore both domestic and international investing, knowing how lot sizes work is more relevant than ever.

What Is a Lot in Securities Trading?

A ‘lot’ refers to a standardised number of units of a security traded as a single transaction. On the ASX, the typical ‘standard market parcel’—often called a ’round lot’—is 100 shares. However, in the modern era of online brokerages, fractional lots and custom lot sizes have become more common, especially for international shares and ETFs.

Standard Lot: Traditionally 100 shares on the ASX.
Odd Lot: Any quantity less than the standard lot (e.g., 37 shares).
Block Trade: Large transactions, often institutional, that far exceed standard lots (e.g., 10,000 shares).

Why does this matter? Lot sizes can affect order execution, brokerage fees, and even the ability to participate in certain corporate actions.

How Lot Sizes Impact Trading in 2025

With the rise of low-cost trading apps and fractional investing platforms in Australia, the rigidness of lot sizes has softened. In 2025, most retail investors can buy odd lots or even fractions of a share in some markets. However, there are still key implications to consider:

Order Execution: Standard lots often receive priority in trade matching. Odd lots may execute at less favourable prices, especially in less liquid stocks.
Brokerage Fees: Some brokers still charge higher fees for odd-lot trades or minimum brokerage for small trades. Always check the fee schedule before placing an order.
Corporate Actions: Participation in rights issues or buybacks may require holdings in standard lots.

For example, if you’re trading on the US market via an Australian brokerage, you might encounter lot sizes of 1 share or even fractional shares (e.g., 0.25 of an Apple share). But on the ASX, the minimum parcel rule (currently $500 worth of shares for a new holding) is still in force for initial purchases, which can influence how many shares you buy in your first trade.

Recent Policy and Market Developments

In 2025, the ASX has maintained its minimum parcel requirement, but several fintech brokers have introduced innovative solutions to help retail investors access global markets with smaller amounts. This trend is mirrored internationally, where exchanges like the NYSE and NASDAQ have embraced fractional trading, lowering the entry barrier for retail investors.

Key updates affecting Australian investors in 2025 include:

ASX Minimum Parcel: Still set at $500 for new holdings, but ongoing trades can be for any amount.
International Brokers: Many now allow Australians to buy fractions of US or European shares, making global diversification easier than ever.
ETF Trading: Some ETF providers have begun offering fractional units, allowing investors to build diversified portfolios with minimal capital.

These changes mean investors should review their broker’s terms and the specific rules of each market they trade in, as lot size conventions and requirements can vary widely.

Practical Tips for Navigating Lot Sizes

Check the minimum parcel size for new investments on the ASX to avoid rejected orders.
Consider brokerage fees for small or odd-lot trades—they can erode returns on small transactions.
If you plan to participate in corporate actions, ensure your holdings meet any lot size requirements.
For international trades, review whether your broker supports fractional investing and how lot sizes affect order execution.

For example, if you want to buy $300 worth of CSL shares on the ASX as a new holding, your order may not be accepted since it doesn’t meet the $500 minimum parcel. Conversely, if you want to invest $100 in US-listed Tesla shares, your broker may facilitate this via fractional trading—even if that equates to 0.2 of a share.

Conclusion: Why Lot Sizes Still Matter

While technology and policy shifts in 2025 have made investing more accessible, understanding the basics of lot sizes can help you avoid unnecessary costs and ensure smoother trading. Whether you’re trading blue chips on the ASX or dabbling in US tech stocks via fractional shares, knowing how lots work is still a vital part of smart investing.