Understudy: Investing Practice

A practice brokerage account for beginners. Place real-style orders with practice money, move the clock yourself, and learn each idea from the trade you just made.

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posted an update —

Update from Thursday, Sept. 17, 2026

Understudy has four investment paths. Stocks shipped in 1.0. Real Estate, Business and Bonds have been blocked on the same two questions since I scoped them: what do the screens look like, and where do the numbers come from?

Both closed today.

25 artboards

Ten for Real Estate, eight for Business, seven for Bonds. Real Estate gets the most because it has the most to teach — pre-approval, listings, comps, offer, inspection, closing costs, and equity over time.

The sourcing rule

This was the harder half. The problem isn't finding financial data — it's that almost none of it can legally ship inside an app binary. Case-Shiller belongs to S&P. PMMS belongs to Freddie Mac. Corporate bond yields belong to Moody's and ICE. Every one of them forbids redistribution, and shipping a binary is redistribution.

I hit this same wall for stocks back in round 24. It's why Understudy's individual stocks are fictional.

So here's the rule I settled on: real where a public-domain series exists, modeled where it must be, labeled either way, and never a third-party feed inside the binary.

  • Real estate — FHFA House Price Index (a federal work, public domain) for prices, HUD Fair Market Rents for rent. The mortgage rate is modeled: the bundled 10-year Treasury plus a documented spread.
  • Bonds — the Fed's H.15 Treasury yields, already bundled daily since 1990, plus TreasuryDirect auction results as dated anchors. Corporate and municipal issuers are fictional, priced as the matching Treasury plus a credit spread by rating.
  • Business — IRS Statistics of Income expense-to-receipts ratios, BLS establishment survival rates for the failure hazard, H.15 prime plus the published SBA 7(a) maximum spread for loans.

Every price surface in the app says whether a number is historical or simulated. Business additionally keeps its ILLUSTRATIVE chip — the grounding is what lets that chip say "grounded in public data" instead of "made up."

Also today: moved to a trunk-based git flow and tagged v1.0.0.

1.0 is still in App Review.

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