Buying Power
What Is Buying Power?
The total amount of capital available to an investor to purchase securities, including cash in the account and the margin (loan) available from the brokerage.
Buying power, also known as "excess equity," represents the maximum dollar amount of securities a trader can purchase without depositing additional funds. It is not just the cash in your account; it is your cash *plus* the leverage your broker is willing to lend you. For example, if you have $10,000 cash in a margin account, your buying power is typically $20,000. This allows you to control more stock than you could with cash alone, amplifying both potential gains and potential losses. Buying power is dynamic; it changes instantly as the value of your positions fluctuates or as you enter and exit trades.
Key Takeaways
- Buying power is the sum of cash held and the maximum margin loan available.
- In a standard margin account, buying power for stocks is typically 2x the cash equity (Regulation T).
- For day traders (Pattern Day Traders), buying power can be up to 4x the maintenance margin excess.
- Exceeding buying power results in a margin call or a trade rejection.
- Buying power varies by asset class; options are often non-marginable (1:1), while forex can be highly leveraged (50:1).
How Buying Power Works
Buying power is governed by Federal Reserve Regulation T and broker-specific house rules. 1. Cash Accounts: Buying power = Cash Balance. You cannot borrow money. 2. Margin Accounts (Overnight): Buying power = 2x Equity. If you hold positions overnight, you can leverage up to 2:1. 3. Pattern Day Trader (PDT) Accounts: Buying power = 4x Maintenance Margin Excess. If you are flagged as a PDT (account > $25,000), you get 4:1 leverage for intraday trades. 4. Portfolio Margin: A risk-based model for advanced traders that calculates buying power based on the theoretical risk of the entire portfolio, often allowing for leverage greater than 4:1 or 6:1.
Key Elements of Calculation
The calculation depends on the type of security: * Fully Marginable Stocks: These use standard buying power. * Hard-to-Borrow Stocks: The broker may require 100% cash (no margin), reducing buying power for that specific trade. * Options: Buying calls or puts usually requires 100% cash. Selling options (writing) uses buying power based on the risk of the position. * Futures/Forex: These use "span margin" or fixed lot margins, which function differently than equity buying power.
Important Considerations: Risk Management
Just because you *have* buying power doesn't mean you should *use* all of it. Using max buying power (max leverage) is extremely risky. A small move against you can trigger a margin call, forcing the broker to liquidate your positions at a loss without your permission. Prudent traders often keep a "cushion" of unused buying power to handle volatility. If your account equity falls below the maintenance requirement (usually 25%), your buying power drops to zero, and you must deposit cash.
Real-World Example: Using Leverage
A trader opens a margin account with $10,000 cash.
Buying Power Reduction (BPR)
When selling options (e.g., credit spreads or naked puts), brokers use the term "Buying Power Reduction" (BPR). This is the amount of capital "locked up" to hold the trade. It is the collateral required to cover potential losses. If a trade has a BPR of $500, your available buying power decreases by $500 when you enter the trade. If the trade moves against you, the BPR may increase, further reducing your available funds.
Common Beginner Mistakes
Avoid these errors when managing buying power:
- Maxing out buying power on a single trade (Lack of diversification).
- Assuming Day Trading Buying Power (4x) can be held overnight (It cannot; positions must be reduced to 2x by market close).
- Forgetting that margin interest is charged on the borrowed portion of buying power.
- Trading volatile stocks without checking if they have higher margin requirements (e.g., 50% or 100% instead of 25%).
FAQs
No. You can only withdraw your "cash available for withdrawal." Buying power includes borrowed money (margin) that belongs to the broker. If you withdraw cash, your buying power will decrease by a multiple of that withdrawal (e.g., withdrawing $1,000 reduces buying power by $2,000).
If you exceed your Day Trading Buying Power (DTBP), you will receive a "Day Trading Call." You will have 5 business days to deposit funds to meet the call. Until then, your account is restricted to "cash-only" trading (buying power = cash) or 2x margin.
Brokers assign different "margin requirements" to stocks based on their volatility and risk. A blue-chip stock might require 30% margin (high buying power), while a volatile penny stock might require 100% margin (low/no buying power). This protects the broker from lending on risky assets.
The primary way is to deposit more cash or marginable securities into your account. Alternatively, closing existing positions frees up the buying power used for those trades. Beware of "margin relief" strategies that only temporarily boost BP.
This refers to the amount available to purchase securities that cannot be bought on margin (like penny stocks, some IPOs, or options). This number is usually equal to your settled cash balance.
The Bottom Line
Buying power is the fuel for your trading engine. Investors looking to leverage their returns must understand how it is calculated. Buying power is the practice of utilizing borrowed capital to increase position size. Through effective management, it allows for greater capital efficiency and profit potential. On the other hand, mismanaging buying power is the fastest way to blow up an account via margin calls. By respecting leverage limits and understanding the difference between cash and margin, traders can use buying power as a tool rather than a trap.
Related Terms
More in Trading Basics
At a Glance
Key Takeaways
- Buying power is the sum of cash held and the maximum margin loan available.
- In a standard margin account, buying power for stocks is typically 2x the cash equity (Regulation T).
- For day traders (Pattern Day Traders), buying power can be up to 4x the maintenance margin excess.
- Exceeding buying power results in a margin call or a trade rejection.