What Is a Margin Maintenance Requirement Percentage?
A margin account doesn’t just need enough value to cover the initial purchase — it needs to keep clearing a bar that’s checked continuously for as long as the position is open.
The short answer
A margin maintenance requirement percentage is the minimum share of a position’s total value that must be covered by an account’s own equity at all times, not just at the moment a trade is placed. It’s set by the broker, generally in line with or above whatever regulatory minimum applies, and it’s checked continuously as prices move rather than on any fixed schedule. Falling below that percentage is what triggers a maintenance call.
How the percentage is applied
The maintenance requirement is expressed as a share of the position’s current market value, not the value at purchase. Suppose a broker sets a maintenance requirement of 30% for a particular security — an account holding a $10,000 position in that security would need at least $3,000 of its own margin equity behind it at any given moment, not just when the position was first opened. As the position’s market value changes, so does the dollar amount required to satisfy that same 30% threshold.
Why the percentage isn’t the same for every security
Brokers typically don’t apply one uniform requirement across an entire account. Securities considered more volatile or less liquid often carry higher maintenance requirements, since a sharp price swing in those holdings could erode equity faster than it would in a steadier position. A concentrated position can also push the effective requirement higher for that portion of the account. These figures are set individually by each broker and by applicable regulatory rules, both of which can change over time, so there’s no single percentage that applies universally or permanently.
What happens when equity falls below the line
Once an account’s equity ratio drops below the maintenance requirement, the broker typically issues a call for additional funds or securities to bring the account back into compliance. If that call isn’t met — whether because the account holder doesn’t respond quickly enough or the shortfall grows faster than it can be addressed — the broker generally has the authority to sell positions without further notice, a process covered in more detail in how a broker can sell securities on a margin call.
Why this figure deserves ongoing attention
Because the requirement is checked continuously rather than periodically, an account that was comfortably above its maintenance threshold one day can fall below it the next purely because of price movement, without any new trading activity. This is part of why maintenance requirements are often discussed alongside the broader risks of buying on margin — the requirement itself doesn’t change minute to minute, but the account’s position relative to it can.
The takeaway
A margin maintenance requirement percentage is a floor that has to hold up continuously, not a box checked once at the start of a trade. Understanding how that floor is calculated — and that it can vary by security and by broker — makes it easier to see why margin accounts require more ongoing attention than a standard cash account.