Both let you borrow against a portfolio, and both can be called. Here is how each one works, and a third structure worth knowing about before you choose.
Both a securities-based line of credit and a margin loan let you spend money without selling your investments. They are secured by the same thing: the portfolio you already own. The difference that matters is what happens after you borrow.
A margin loan is open-ended and can be called at any time. A securities-based line of credit, usually shortened to SBLOC, is also open-ended and can also be called. Neither one has a date when the cost is settled and the debt is gone. That is the part most comparison pages skip, and it is the part that decides what you pay.
You borrow against the securities in your brokerage account. Your broker sets a maintenance requirement, which is the minimum amount of equity the account must hold. If the portfolio falls below that line, the broker issues a margin call and can sell your positions to bring the account back into compliance.
Two practical points:
Margin is convenient because it is already inside the account. That convenience is priced into the rate and into the liquidation terms.
A SBLOC is a revolving credit line issued by a bank against a pledged brokerage account. It sits outside the brokerage account, so it does not show up as margin debt and it is not governed by the same margin rules.
Most SBLOCs carry a non-purpose restriction: the money cannot be used to buy securities. It can fund a home, a tax bill, a business expense or a renovation.
Typical features:
A SBLOC is generally easier to live with than margin during a drawdown, because the LTV limit on a diversified portfolio is usually lower than a margin maintenance requirement. It is still callable.
The point that matters. A margin loan and a SBLOC both leave you with a variable balance at a variable rate, on no fixed end date. For a need with a deadline, such as a tax payment due in April, the total cost is unknown when you start.
Side by side
Terms vary by lender and by account. Always ask for the full economics for your specific amount.
There is a structure where the interest rate, the maturity date and the exact amount repaid are all set when you begin. It is built from options rather than from a bank credit line, and it is often called box spread financing.
Here is the mechanism in plain terms. A box spread is a set of four options positions that, together, produce a known payoff on a known future date. Traded in the right combination, it behaves like a loan: you receive cash now and owe a fixed amount at expiration. The rate is set by the options market rather than by a broker's rate card.
Three properties of a fixed-maturity structure are worth understanding:
This is the structure InvestedFlex uses, and it is why the site talks about dated maturities and full economics rather than a headline rate.
Start with the shape of your need, not the rate.
Open-ended, amounts that vary, indefinite timeline. A line of credit fits. You may want to draw, repay and draw again.
A bounded need with a date attached. A tax bill, a closing date, a tuition payment. Fixed maturity gives you a cost you can plan around, which usually matters more than a few basis points.
A concentrated single stock. Ask what the LTV would be under each option. A concentrated position is treated differently by every lender, and the difference can be larger than the rate difference.
Then ask each provider for the full economics: the rate, the maturity, every fee, what happens if you close early, and what triggers a call. A rate without those terms is not a comparison.
A private review compares the paths for your specific holdings, amount and timeline. Indicative pricing, dated.