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Preferences

Preferences lets you save simulation defaults for each symbol, including starting cash and trading costs. Use these settings to match the assumptions you want to test.

Set your defaults​

  1. Open Preferences in MesoSim from your account menu.
  2. Choose Settings for symbol and adjust the values for that symbol.
  3. Select Save and confirm the change.
Save before switching symbols

Save your changes before selecting another symbol or leaving the page.

When preferences apply​

Simple run and Templated run use the saved preferences for the selected symbol. Changing the symbol through the AI Editor's symbol selector also applies that symbol's saved cash and simulation settings.

A run uses the values in its Strategy Definition. Review them before submitting, especially when working with an AI-generated draft or cloning a previous run. Changing preferences does not update existing backtest results.

Cash and trading costs​

Initial cash​

The starting capital for the simulation, stored in Backtest.Cash.

Fill model​

The fill model determines the simulated price of each buy or sell:

  • Mid Price: fills at the midpoint between the bid and ask.
  • Bid/Ask: fills buys at the ask and sells at the bid.

Use these assumptions to explore how execution prices affect your results. See fill models for the full reference.

Slippage​

Slippage adds an extra cost to the price determined by the fill model, for each leg. It increases the price of a buy and reduces the price of a sell.

For example, with a mid-price of $1.00 and slippage of $0.10, the simulated fill is $1.10 for a buy or $0.90 for a sell. Slippage also applies when using the Bid/Ask fill model.

For a four-leg structure with one contract per leg, a total slippage assumption of $0.05 in option-price units corresponds to $0.0125 per leg ($0.05 ÷ 4). This is an example of allocating a chosen cost assumption, rather than an estimate of typical fills.

Commission​

Set the commission per contract to match your brokerage costs. See commission settings for details.

Risk traces​

Trace Collection Interval sets how often the simulation records Risk Traces for later analysis. See Position Monitor for how to use them.

Leg selection and margin​

Set leg selection constraints and the margin model directly in the Strategy Definition, using Settings.Core.LegSelectionConstraint and Settings.Core.Margin.

These controls are currently displayed on the Preferences page, but changes to them are not saved there.

Continue with Create and run a backtest to apply your settings and test a strategy.