Simulated account (B-book)
An evaluation or funded account that mirrors live market prices internally rather than placing your orders on the real venue.
Almost every prop firm — in forex, futures and now prediction markets — runs a simulated, or B-book, account. Your fills happen inside the firm's system rather than on the live venue, even when the quotes are priced off the real market. This is the industry-standard model, not a red flag, but it means you are not trading your own capital on-chain.
Several prediction-market firms, including FundedPoly, PolyFundr and PropMarket, price their simulated accounts off Polymarket's live order book, so the odds you see are real even though the fills are internal. We label execution honestly for every firm and do not call any of them 'real capital'.
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Definition reviewed June 2026. Rules change often — confirm specifics on each firm’s own site.
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