How SBLOC Borrowing Works
The credit line is the easy part. The maintenance threshold is the number that actually matters, and it rarely gets explained clearly.
1. Find your eligible collateral value
Lenders don't count every holding equally. Diversified, liquid, exchange-listed stock and bond positions usually count in full; concentrated single-stock positions, restricted or thinly-traded shares often count less or not at all.
2. Apply the advance rate
This is the lender's loan-to-value ceiling — commonly 50–95% depending on how the portfolio is built. A diversified bond-heavy portfolio usually gets a higher advance rate than a portfolio concentrated in one volatile stock.
3. Decide the draw, not the max
The credit line is a ceiling, not a target. Every dollar drawn narrows the gap between the loan and the maintenance threshold — the cushion that protects you from a market dip forcing a call.
4. Locate the maintenance threshold in the agreement
This is the balance-to-portfolio ratio the lender will not let you cross. It is usually tighter than the initial advance rate, which is exactly what creates risk even for borrowers who started well within their limit.
5. Work backward to a drop percentage
Divide the draw by the maintenance threshold to find the portfolio value that would trigger a call, then compare that to today's value. That gap — expressed as a percentage — is the real risk figure, not the interest rate on the line.
6. Remember what a call actually means
Unlike a mortgage margin call, an SBLOC or brokerage margin call can be met by the lender selling holdings without prior notice and without letting you choose which positions go — often at the worst possible moment in a falling market.