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MARGIN, HONESTLY — BORROWED MONEY, REAL TEETH

Lesson 17 of 72 · 6 min read · Stage 2 · Brokers, Accounts & Orders · Updated Oct 21, 2026
STAGE 2 — Brokers, Accounts & Orders · Prerequisite: CASH VS MARGIN — AND THE ONE-DAY SETTLE
TL;DR
  • Margin is a loan from your broker, secured by your own holdings. You pay interest daily, and if your equity falls under the maintenance floor, the broker can sell your positions — without asking, and without waiting for a recovery.
  • The arithmetic is unforgiving: starting at Regulation T's 50%, a 40% fall in the stock leaves your equity at 16.7% of the position — under FINRA's 25% floor. Fall more than half and you owe money beyond everything you deposited.
  • Rule change, June 4, 2026: FINRA retired the $25,000 pattern-day-trader rule and replaced it with intraday margin standards (Regulatory Notice 26-10). Courses still teaching the $25,000 rule as current are out of date.

A loan with a daily interest meter and a trapdoor: how margin really works, why this course starts cash — and the famous $25,000 rule that no longer exists. Margin is borrowing against your house to buy a second house — where the bank revalues both houses every day, and if your equity in the second one thins out, it can force its sale at the worst moment of the worst week, without phoning you first, and mail you the bill if the sale doesn't cover the loan. Every word of that is in the agreement people click through in eleven seconds.

Margin arithmetic panel · diagram · The lesson's worked numbers: $5,000 of yours plus a $5,000 loan, and where FINRA's 25% maintenance floor sits as the price falls.

THE TAKEAWAYS

  • The mechanics: deposit cash, borrow up to the same again for stocks (Regulation T 50% initial margin). Your equity is the position's value minus the loan. The loan does not shrink when the price falls — your equity absorbs the entire fall.
  • FINRA's maintenance floor for long stock positions is 25%: your equity must stay at least a quarter of the position's current value, and brokers may (and do) impose higher ‘house’ floors. Below the floor comes the margin call — and the standard margin agreement lets the broker liquidate immediately, choosing what to sell, without waiting for you to answer the call.
  • Interest is a real, daily cost. One major broker's published margin rates, checked Oct 15, 2026 (Fidelity), ran from 7.50% to 11.825% per year depending on the size of the balance borrowed — charged on money you owe whether your trades win or lose.
  • Why this course starts cash and paper: every Stage 0 statistic was compiled from ordinary accounts. Margin multiplies position size, speeds up every clock in the course, and adds a counterparty who can end your trades for you. Nothing in Stages 0–10 requires it.
RUSTY’S RULE
Never size a position off buying power. Size off your Stage 0 dollar figure — the amount whose total loss changes nothing — and remember the loan is the only participant in your trade who gets paid in every outcome.

WORKED EXAMPLE — STEP BY STEP

  1. The lesson's arithmetic example — the percentages are the actual rules (Regulation T, FINRA Rule 4210); the stock's path is the example. You deposit $5,000 and buy $10,000 of a stock: $5,000 yours, $5,000 borrowed. Your equity is $5,000 — 50% of the position. The graphic draws this as the top bar.
  2. The stock falls 30%: the position is worth $7,000. The loan is still $5,000. Equity = $7,000 − $5,000 = $2,000, which is 28.6% of the position — still above FINRA's 25% floor, but already inside many brokers' higher house floors. A margin call is possible here, not just in theory.
  3. The stock falls 40%: position $6,000, equity $1,000 — 16.7%, under the floor. Margin call: deposit cash or securities immediately, or the broker sells enough of the position to restore the percentage — at $6,000, near the bottom, in their chosen order.
  4. The stock falls 50%: position $5,000, exactly the loan. Your equity is $0 — every dollar you deposited is gone because a stock fell by half. Fall further and your equity goes negative: you owe the broker money on top of a total loss. Cash accounts cannot do this to you. Margin accounts do it by design.
  5. Now run the same falls with cash only, $5,000 in, no loan: −30% leaves $3,500; −40% leaves $3,000; −50% leaves $2,500. Nothing can be sold out from under you and no interest meter runs. Leverage doesn't change the percentage the stock falls — it changes whose money absorbs it, and who holds the trapdoor.
THE TRAP — THE SALE YOU DIDN'T PLACE

The losing variant is the liquidation itself. It executes at the worst prices of the move, in the broker's order, possibly before any ‘call’ reaches you — the agreements allow it, and FINRA's required margin disclosure document (Rule 2264), which every margin customer receives, has brokers warn of exactly this at account opening. Traders describe logging in to find positions gone and a debit balance owed. That is not a malfunction; it is the product working as documented. This course's defence is structural, not clever: a cash account has no trapdoor.

WHAT CHANGED — JUNE 4, 2026: THE $25,000 RULE IS RETIRED

This course's first ‘what changed’ note — dated, and kept dated. THE OLD RULE (2001–2026): make four or more day trades within five business days in a margin account and you were designated a ‘pattern day trader’, required to keep at least $25,000 of equity in the account or face restrictions. THE CHANGE: FINRA Regulatory Notice 26-10 (published April 20, 2026) replaced the day-trading margin requirements in their entirety, effective June 4, 2026. Gone: the day-trade count, the pattern-day-trader label, and the $25,000 minimum. In their place: intraday margin standards — your equity must properly cover the margin on the positions you actually hold intraday, with the ordinary maintenance requirements (like the 25% floor above) still applying overnight. THE CATCH: brokers may phase in their implementation any time up to October 20, 2027, so two brokers can treat the same active trading differently right now — and most older courses and videos still teach the $25,000 rule as if it were law. Check your own broker's current intraday-margin treatment; this note will be re-checked as the phase-in completes.

COMMON BEGINNER MISTAKES

  • Sizing off buying power instead of your own Stage 0 dollar figure. The broker's loan limit is not a risk plan.
  • Assuming a margin call is a polite phone call with a deadline. The agreement allows liquidation first and notification after.
  • Quoting the retired $25,000 pattern-day-trader rule as current law. It was replaced on June 4, 2026 (FINRA Notice 26-10).
  • Forgetting the interest meter: margin costs accrue daily, in winning trades and losing ones alike.

CHECK YOURSELF

Q1. You buy $10,000 of stock with $5,000 borrowed. It falls 40%. Your equity is…

Q2. Your equity falls under the maintenance floor. The broker may…

Q3. As of June 4, 2026, the $25,000 pattern-day-trader rule…

DO IT — RUN THE SEESAW ON PAPER

With pen and paper, pick a deposit you'd actually consider — say $2,000. Borrow the same again on paper and run the falls: −20%, −30%, −40%, −50%. Write your equity at each step and mark where it crosses FINRA's 25% floor. Then write one sentence in your journal: which account type this course uses until Stage 10, and why. (Cash — because the trapdoor isn't worth renting.)

Download this lesson’s cheat sheet (PDF)

STAGE 2 — BROKERS, ACCOUNTS & ORDERS — ALL 6 LESSONS

  1. 15WHAT A BROKER ACTUALLY DOES5 min read
  2. 16CASH VS MARGIN — AND THE ONE-DAY SETTLE5 min read
  3. 17MARGIN, HONESTLY — BORROWED MONEY, REAL TEETHYOU ARE HERE
  4. 18MARKET VS LIMIT — TWO DOORS INTO THE MARKET5 min read
  5. 19STOPS, STOP-LIMITS, AND THE FINE PRINT6 min read
  6. 20READING A QUOTE — AND WHAT THE ROUND TRIP COSTS6 min read