us-market-ruleslisted

US trading rules that decide whether a strategy is executable at all - short-sale restrictions, margin, settlement, day-trading limits, wash sales, and what a data licence lets you keep. TRIGGER - can I short this, locate, hard to borrow, borrow fee, short interest, Reg SHO, uptick rule, SSR, short sale restricted; PDT, pattern day trader, day trade limit; Reg T, initial or maintenance margin, margin call, buying power, leverage limit; T+1, settlement, cash account; wash sale, tax-loss harvesting, after-tax returns; "can I redistribute this data"; may_cache, may_redistribute, market data licence; presenting or publishing backtested performance, Marketing Rule. Two of the most-cited rules moved in 2024-2026, so a training-prior answer is usually stale. US ONLY - SKIP for short-selling bans or calendars in Asia (asia-pacific-markets), for A-share T+1 and price limits (china-trading-stack) and for the order-safety mechanics of actually sending an order (broker-execution-apis).
howard-lynn-ye/fin-skills · ★ 1 · AI & Automation · score 77

Install: claude install-skill howard-lynn-ye/fin-skills

# US market rules Engineering context, **not legal advice** — confirm against the primary release before relying on it. Verified 2026-09-04. **Key every rule to a date.** A backtest over 2015 must apply the 2015 rulebook; a live path in 2026 applies the current one. The two most-cited rules in trading tutorials both moved recently, so a model answering from its training prior will usually be wrong about them. ## 1. 🚨 Changed recently — most tutorials are stale | Rule | Status | Consequence | |---|---|---| | **Pattern Day Trader (PDT)** | 🚨 **ELIMINATED effective 2026-06-04** (SEC Release **34-105226**), replaced by intraday margin | **Keep PDT in the backtester for pre-2026-06-04 periods; remove it from live paths.** Any strategy previously rejected for needing >3 day-trades/5 days on a <$25k account needs re-evaluating | | **Settlement** | ✅ **T+1 since 2024-05-28** (was T+2) | Free-riding and good-faith-violation windows shortened; cash-account strategies that relied on T+2 float no longer work | | **SEC predictive-data-analytics / AI proposal** | ✅ **WITHDRAWN 2025-06-17** | Do not design to it | | **Marketing Rule (206(4)-1)** | In force, with **March 2025 and January 2026 FAQs** | Governs how hypothetical/backtested performance may be presented — §4 | ## 2. 🚨 Reg SHO Rule 201 breaks the backtests that claim the most edge After a security drops **10% intraday** from the prior close, short sales may only execute **above the national best bid** for the rest of that