---
title: "Trading conventions and lot sizes"
slug: "trading-conventions"
updated: 2025-02-20T15:47:06Z
published: 2025-02-20T15:47:06Z
canonical: "support.lusid.com/trading-conventions"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://support.lusid.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Trading conventions and lot sizes

When mastering certain types of instrument in LUSID, you can specify lot size rules for trading those instruments. These rules determine a minimum order size and minimum increment (lot size) that LUSID uses when generating orders and allocating trades.

You can specify this information in the `tradingConventions` section of each [instrument definition](/v1/docs/how-do-i-master-an-instrument). The `tradingConventions` section is available for the following instrument types:

- [Bond](/v1/docs/modelling-fixed-rate-vanilla-bonds-in-lusid)
- [ComplexBond](/v1/docs/modelling-complex-bonds-in-lusid)
- [ExchangeTradedOption](/v1/docs/modelling-exchange-traded-options-in-lusid)
- [Future](/v1/docs/modelling-exchange-traded-futures-and-options-in-lusid)
- [InflationLinkedBond](/v1/docs/modelling-inflation-linked-bonds-in-lusid)
- *More coming soon*

> [!NOTE]
> **Note:** Currently, [Equity](/v1/docs/modelling-equities-in-lusid) and [ContractForDifference](/v1/docs/modelling-cfds-in-lusid) instruments use the `lotSize` field instead of `tradingConventions`.

## Adding trading conventions to an instrument

You can define `tradingConventions` for an instrument within the `definition` using the [UpsertInstruments](https://www.lusid.com/docs/api/lusid/endpoints/instruments/UpsertInstruments) API.

For example, you could specify the following `definition` for a bond to ensure LUSID generates orders with a minimum size of 10 and increment of 5:

```json
{
 "startDate": "2019-02-15T00:00:00.0000000+00:00",
  "maturityDate": "2049-02-15T00:00:00.0000000+00:00",
  "domCcy": "EUR",
  "flowConventions": { ... },
  "principal": 1,
  "couponRate": 0.03,
  "tradingConventions": {
    "priceScaleFactor": 1,
    "minimumOrderSize": 10,
    "minimumOrderIncrement": 5
  },
  "instrumentType": "Bond"
}
```

> [!NOTE]
> **Note:** LUSID uses `priceScaleFactor` when calculating the effect of open orders and booking trades. If not specified, the value defaults to `1`.

Some instrument types have a `lotSize` field instead of `tradingConventions`. For such instruments, you might specify the following `definition` to ensure LUSID generates orders with a round lot size of 20:

```json
{
  "domCcy": "EUR",
  "lotSize": 20,
  "instrumentType": "Equity"
}
```

## Rebalance dashboard

When you rebalance your portfolio, the Rebalance dashboard rounds your orders to meet the minimum order size and increment size for each instrument.

For example, imagine you [use the Rebalance control panel](/v1/docs/configuring-rebalancing-use-cases-in-the-rebalance-dashboard) to spend 50,000 EUR across two instruments:

- An equity with a defined lot size of 20
- A bond with a minimum order size of 10 and minimum order increment of 5

LUSID displays a resulting order quantity for each instrument that adheres to the rounding rules:

![](https://cdn.document360.io/d575ad81-c0ed-4980-bbd1-d59ac5c3de82/Images/Documentation/image(525).png?sv=2026-02-06&spr=https&st=2026-11-09T05%3A49%3A58Z&se=2026-11-09T06%3A49%3A58Z&sr=c&sp=r&sig=z1PqrpIwzecYcZGCOD%2FfoilMLa0abfEwTa9ii4mQknI%3D)

You can click on the warning icon in the **Breaches** column to see the rounding rules applied to each instrument, and optionally override them:

![](https://cdn.document360.io/d575ad81-c0ed-4980-bbd1-d59ac5c3de82/Images/Documentation/image(518).png?sv=2026-02-06&spr=https&st=2026-11-09T05%3A49%3A58Z&se=2026-11-09T06%3A49%3A58Z&sr=c&sp=r&sig=z1PqrpIwzecYcZGCOD%2FfoilMLa0abfEwTa9ii4mQknI%3D)

![](https://cdn.document360.io/d575ad81-c0ed-4980-bbd1-d59ac5c3de82/Images/Documentation/image(519).png?sv=2026-02-06&spr=https&st=2026-11-09T05%3A49%3A58Z&se=2026-11-09T06%3A49%3A58Z&sr=c&sp=r&sig=z1PqrpIwzecYcZGCOD%2FfoilMLa0abfEwTa9ii4mQknI%3D)

Note the following:

- If you are selling out of a whole position, for example setting **Target Exposure** to **0**, LUSID ignores the rounding rules and sells out of the entire position.
- Trading conventions and lot sizes support sizes below 1. This allows you to create fractional orders for specific instruments, for example funds.

> [!NOTE]
> Manually entering order quantities
> 
> If you manually enter order quantities in the Rebalance dashboard, the dashboard warns you if your orders do not adhere to the minimum order or increment size.
> 
> The dashboard does **not** automatically adjust manually-entered order quantities. ![](https://cdn.document360.io/d575ad81-c0ed-4980-bbd1-d59ac5c3de82/Images/Documentation/image(514).png?sv=2026-02-06&spr=https&st=2026-11-09T05%3A49%3A58Z&se=2026-11-09T06%3A49%3A58Z&sr=c&sp=r&sig=z1PqrpIwzecYcZGCOD%2FfoilMLa0abfEwTa9ii4mQknI%3D)

## Order Blotter

The **Order Blotter** prevents you from creating orders that do not adhere to the defined trading conventions for each instrument.

![](https://cdn.document360.io/d575ad81-c0ed-4980-bbd1-d59ac5c3de82/Images/Documentation/image(520).png?sv=2026-02-06&spr=https&st=2026-11-09T05%3A49%3A58Z&se=2026-11-09T06%3A49%3A58Z&sr=c&sp=r&sig=z1PqrpIwzecYcZGCOD%2FfoilMLa0abfEwTa9ii4mQknI%3D)

## Post-trade

[Allocation algorithms](/v1/docs/allocating-fills-automatically-using-allocation-algorithms) also adhere to the defined lot size/trading conventions when allocating fills.