MesoSim v3.1: Integrated AI Assistant and more
On March 18, 2026, we are releasing MesoSim v3.1. This update includes more than 30 improvements and fixes across four areas:
- AI enablement
- Mobile usability
- American options modeling
- Multi-timeframe support
The headline feature in this release is the direct integration of the MesoSim AI Assistant into MesoSim Portal.
MesoSim AI Assistant
Brief History
We launched our first MesoSim-specific ChatGPT assistant in 2024, built on top of GPT-4. Since then, we have continuously evolved it to work as a natural-language interface to our simulator.
The ChatGPT-based assistant became materially more capable once GPT-5's extended reasoning features became available in 2025. The current ChatGPT-hosted version is already highly effective for strategy development, debugging, and product guidance. You can find more information about this assistant in this Meso Markets thread.
With MesoSim v3.1, we are taking the next step by bringing the assistant directly into MesoSim Portal. You can now develop, extend, and analyze trading strategies using natural language, for example:
Build an SPX Put Broken Wing Butterfly at 10 / 15 / 18 deltas at 60 DTE. Hold it for 30 days. Set Profit Target to $200, Stop Loss to $400
In turn, the assistant will generate the corresponding Strategy Definition for you.
The updated workflow is documented in our Getting Started Guide.
Over the next few weeks, we will calibrate usage limits based on real-world demand so the default allocation matches the needs of most users. The built-in Assistant is now available to users on the Standard and Advanced plans.
The ChatGPT-hosted MesoSim AI Assistant remains a useful extension. It is available to users without an active subscription and to prospective customers who want to understand the platform before committing to a paid plan.
FundPro customers have been gaining additional benefits since 2024 by using our APIs with coding assistants such as OpenAI Codex, Google Gemini, and Anthropic Claude for strategy development and research automation. These coding agents have direct access to FundPro services, allowing them to perform complex tasks such as backtest execution, event log analysis, and strategy extension.
Improved modeling and simulation
We also expanded the simulation engine in two important areas.
American options support
MesoSim now provides more accurate modeling for American-style equity options, including options on stocks affected by splits and dividends. With the new pricer, FundPro customers can bring their own equity options data and model these contracts accurately.
30-minute resolution and more
Until now, MesoSim supported daily and 5-minute update frequencies. v3.1 adds a 30-minute resolution, giving users a practical middle ground between speed and accuracy for intraday simulations.
Alongside these headline items, MesoSim-v3.1 also includes a range of mobile usability improvements and smaller workflow refinements across the portal.