Margin Account¶
A margin account is a brokerage account that allows a trader to borrow funds from their broker to purchase securities, using the account's existing cash and holdings as collateral. The broker charges interest on the borrowed amount, called the debit balance, typically calculated as the broker call rate plus a spread. Unlike a cash account, a margin account enables leverage, which amplifies both gains and losses.
HOW IT WORKS¶
Account equity is calculated as the total market value of securities minus the debit balance. Two thresholds govern the account: the initial margin requirement, set at 50% for most stocks under Regulation T, and the maintenance margin, the minimum equity percentage the account must hold at all times — FINRA requires 25%, though most brokers impose a house requirement of 30–40%. When equity falls below the maintenance margin, the broker issues a margin call — a demand, not a request — requiring the trader to deposit cash or liquidate positions. The price at which a margin call triggers on a long position is:
For example, a $20,000 position funded with $10,000 cash and a $10,000 loan at a 30% maintenance margin triggers a call at $14,285.71. Brokers may liquidate positions without consent to restore compliance, and gap-down opens can push equity below zero, leaving the trader liable for the resulting debit balance.
IN TAPEBOARD¶
Tapeboard displays margin account metrics in the Account panel, including your current equity, debit balance, and available margin buying power. The margin call price for each open position is surfaced directly in the Positions table so you can monitor proximity to the maintenance threshold in real time. Alerts can be configured to notify you when a position approaches its margin call price, giving you time to act before forced liquidation occurs.