The options market-making arm of Walleye, founded in Minnesota in 2005. Thousands of lines a quarter, much of it put/call inventory carried against customer flow rather than directional bets.
About MarketGrep
MarketGrep (市场脉动) is a free market-environment dashboard published by GREP24. It refreshes after every US trading session and condenses breadth, momentum, the volatility regime, retail sentiment and a turbulence index into one reading. Every signal is descriptive — nothing on the site is a buy or sell recommendation.
Programmatic access: the JSON API is documented at /developers (OpenAPI schema at /openapi.json); AI agents should start from /llms.txt. Any page returns Markdown when requested with an Accept: text/markdown header.