What happens to collateral after you pledge it

By Ryan Hogan, founder of Tungsten LLC. Published September 22, 2026.

Borrowing against an asset sounds simple. You pledge something you own, the lender advances cash, and you get the asset back when you repay. In markets, the arrangement has more moving parts, and those parts explain a surprising share of what goes wrong in a crisis.

Three ideas do most of the work: the discount a lender applies to your collateral, the right to keep using an asset you have pledged, and the lender's ability to reuse that same asset for its own borrowing.

The haircut

A lender rarely advances the full market value of collateral. It applies a haircut, lending less than the asset is worth so that a fall in price still leaves the loan covered.

Pledge $100 million of short-dated government bonds and you might borrow $98 million. Pledge $100 million of high-yield corporate bonds and you might borrow $85 million. The difference reflects how far the price could move before the lender could sell, and how easily it could sell at all.

Haircuts are not fixed. They widen when prices get volatile or when the lender's own funding gets tighter, and a wider haircut forces the borrower to post more collateral or shrink the position. That is why haircuts show up in accounts of crises: they are a channel through which stress spreads from one firm to another without any loan going bad.

Hypothecation: pledging without giving up use

Hypothecation is pledging an asset as collateral while keeping ownership and use of it. A mortgage is the familiar version. The house secures the loan, the lender can take it if you default, and in the meantime you live there.

In brokerage accounts the same structure appears in margin lending. Buy securities on margin and those securities are pledged to the broker. You still receive the dividends and still choose when to sell, but the broker holds a claim on them, and if the account falls below a maintenance level the broker can sell without asking.

The arrangement is efficient. It lets one pool of assets support both an investment position and a loan. It also means the asset is doing two jobs at once, which matters when someone else has a claim on it too.

Rehypothecation: the same asset, again

Here the chain extends. A broker holding client collateral may pledge that same collateral to fund its own borrowing. That is rehypothecation, and it is ordinary practice, subject to regulatory limits that vary by jurisdiction.

Follow the chain. A hedge fund pledges bonds to its prime broker. The prime broker pledges those bonds to a bank. The bank uses them as collateral in the repo market. One set of bonds now supports three layers of credit. The system funds more activity with less capital, which is the point.

The cost appears when the chain has to unwind. If a firm in the middle fails, the question of who has a claim on the bonds becomes a legal problem, resolved over months. Clients of Lehman Brothers' London operation spent years recovering assets that had been rehypothecated, and the episode is why prime brokerage agreements are now read closely for exactly this clause.

Why this determines who survives

Collateral chains connect firms that have no direct relationship. A fund that never traded with a failing bank can still be affected, because the bank held collateral that the fund's broker had pledged onward.

Three effects follow.

Stress transmits through haircuts rather than defaults. Raising haircuts across a market forces every borrower to post more or sell, regardless of whether anyone has missed a payment.

Good collateral gets scarce. In a panic, lenders accept a narrower range of assets. Government bonds stay acceptable; almost everything else takes a bigger discount or stops being usable. Borrowers holding the wrong collateral lose access to funding even though their assets have not defaulted.

Legal form decides outcomes. Whether an asset was segregated, hypothecated or rehypothecated determines whether a client gets it back quickly, slowly, or as an unsecured claim. That distinction is invisible in calm markets and decisive in a failure.

What to check if you have a margin account

Individual investors meet this system through margin lending, and the account agreement is where the terms live.

Segregated or not. Fully paid securities in a US cash account are generally required to be segregated from the broker's own assets. Margin securities can be pledged by the broker, within limits set by regulation.

The maintenance requirement. The agreement says how far the account can fall before the broker acts, and it almost always says the broker can sell without contacting you first.

What counts as collateral. Brokers can change which securities are marginable and what discount they apply, sometimes with little notice, usually in the conditions where it hurts most.

Borrowing against a portfolio is a legitimate tool. The risk is not the borrowing itself; it is that the terms can tighten at the same moment the assets fall, and the two together force a sale at the bottom.

The terms involved

Collateral is what secures a loan. Haircut is the discount applied to it. Hypothecation is pledging it while keeping use. Repo is the short-term secured borrowing where much of this happens. Margin is the credit extended against securities.

The archive has the questions these came from, and the glossary defines each one.