Sigma vs Quiver Quant: which insider-trades API is right for you?

Quiver Quant pioneered the "alt-data for retail" idea: an API bundling SEC Form 4, Congress trades, DOD contracts, WSB sentiment. It's an excellent US-centric product with a proprietary score. Sigma tackles the same "insider API" wedge from a different angle: multi-market (FR, US, DE, CH, UK), score with a fully public formula, free tier without a key, and a native MCP server Quiver doesn't expose. Your choice depends on your investment universe and your tolerance for black boxes.

Geographic scope

Quiver covers mostly the US: SEC Form 4, lobbying, patents, Congress. If you're building a factor model on the S&P 500, that's largely enough. Sigma aims at the transatlantic investor or quant: one common endpoint returns an Allianz filing (BaFin) with the same structure as a Microsoft Form 4. No more coding five parsers nor mapping five local schemas. FX normalisation (T-date historical rate) lets you aggregate amounts in EUR or USD without bias.

Score: proprietary vs open

Quiver uses a proprietary score, the formula isn't published. That's a valid commercial choice, but it makes internal audit harder ("why is this signal at 84?"). Sigma does the opposite: the composite formula (relative size, insider's historical conviction, role, market cap, sector momentum) is fully documented on /methodologie, with coefficients and bounds. A compliance analyst can reproduce every score by hand. An academic researcher can cite the methodology in a working paper.

Pricing and free tier

Quiver offers paid tiers from ~$10/mo (premium ~$50) with call quotas and historical limits. Sigma offers a Free tier (account required, 15 pages/day, web only, no API), Pro at €19/mo (10k requests, MCP, 5-year history, 1 webhook, real-time alerts) and Quant at €99/mo (100k requests, unlimited webhooks, bulk exports, 5 seats, portfolio attribution). The sweet spot for an AI agent or side project is Pro.

MCP server: the AI-agent edge

As of this page, Sigma is among the first financial-data providers to expose a public MCP (Model Context Protocol) server. Concretely: you plug Claude Desktop, ChatGPT Desktop or Cursor into the Sigma endpoint, and your agent can query insider data in natural language through typed tool calls. Quiver has no equivalent (yet). If your 2026 stack includes an AI agent, that's a meaningful gap.

When to prefer Quiver

If you want US alternative data beyond insiders (Congress, lobbying, government contracts, WSB sentiment), Quiver does all that natively and Sigma doesn't cover those sources. Quiver remains a strong US-market buy if you don't need Sigma's European coverage.

One-line verdict

Quiver Quant is the US alt-data suite; Sigma is the open-formula multi-market insider-trades API designed for AI agents and pan-European quants.