Definition
Account equity is the current net value of an account after combining its cash, marked positions, and other assets and subtracting applicable liabilities.
In market context
Equity changes when market prices move even if no cash transaction occurs, because open positions are usually marked to a current valuation price. It differs from account balance, which generally reflects posted ledger activity, and from available cash or margin, which accounts for restrictions and commitments. On leveraged accounts, falling equity can reduce margin capacity and move the account closer to a warning or liquidation threshold.
Risk context
Displayed equity can change quickly and may not equal the amount obtainable if positions must be closed during volatile or illiquid conditions.
Source
Use the primary source for fuller regulatory or market context.