Warehouse Lending, Explained

A warehouse line is short-term financing that lets a mortgage lender fund a loan at closing before it is sold to an investor or aggregator. The lender draws against the line to close the loan, repays the advance once the loan is sold or delivered, and the capital becomes available again for the next loan. How long that cycle takes, not just the interest rate on the line, is the single biggest driver of what a warehouse facility actually costs an institution.

How warehouse lending actually works

A mortgage lender does not typically fund loans out of its own balance sheet. Instead, it borrows against a warehouse line, a revolving credit facility provided by a bank or other warehouse lender, to fund the loan at closing. The originated loan itself serves as collateral for that advance.

From there, the loan moves through a sequence of steps before it can be sold: final documents are collected, the loan is certified and prepared for delivery, it is shipped to the buyer or aggregator, and the buyer completes its own purchase review before funds are released back to the originator. Once the loan is purchased, the originator repays the warehouse advance, and that capital is freed up to fund the next loan.

The loan itself only needs to be funded once. The capital behind it, however, is committed for the entire time the loan sits on the warehouse line, and every day it sits there has a cost.

Why dwell time is the variable that actually matters

The industry term for how long a loan sits on a warehouse line before it is sold and the advance is repaid is warehouse dwell. Dwell time is driven far more by how long it takes to move a loan through post-close review, certification, delivery, and purchase than by anything related to the loan's underlying credit quality.

Every day of dwell carries a real cost: interest on the warehouse advance itself, hedge costs to protect against rate movement while the loan is held, and the opportunity cost of capital that is committed to one loan instead of being available to fund another. None of that shows up as a single line item most institutions track directly, which is part of why dwell time gets less attention than it deserves relative to its actual cost.

What extends dwell time

Dwell time rarely extends because underwriting itself takes too long. It extends because of everything that happens after the loan closes and before it can actually be sold.

A loan that closes cleanly can still sit for weeks if post-close QC has to independently re-verify facts that were already confirmed during underwriting, if the buyer's purchase review has to reconstruct evidence that already exists somewhere in the file, or if a minor exception discovered during delivery has to be traced back through several parties before it can be resolved. None of that is unusual. It is the normal cost of a system where trust does not travel with the loan, so every participant, from post-close QC to the buyer's diligence team, ends up re-establishing the same facts independently before they are willing to act on them.

Wet funding versus dry funding

Warehouse lending intersects with another distinction worth understanding: wet funding versus dry funding. In a wet-funded closing, the lender disburses loan proceeds at or before closing, before all closing documents have been fully reviewed and finalized, and trailing documents are submitted afterward. In a dry-funded closing, funds are not disbursed until all documentation has been reviewed and confirmed complete. Most states operate on a wet-funding basis; a smaller number require dry funding.

The distinction matters for warehouse dwell because it shapes when the clock actually starts. A wet-funded loan draws against the warehouse line at closing while some documentation is still trailing in, which means the file has to be fully reconciled after the fact before it is ready for delivery, adding a step to the post-close sequence that a dry-funded file has already cleared before the advance is even drawn.

Who provides warehouse lines, and how they manage their own risk

Warehouse lines are typically provided by banks and non-bank warehouse lenders, and they come in two general structures. A committed line obligates the warehouse lender to fund up to an agreed capacity, subject to the terms of the facility. An uncommitted line gives the warehouse lender discretion to decline funding on a given draw, even within the stated facility size, which gives the warehouse lender more flexibility to manage its own risk in a stressed market.

Warehouse lenders manage their exposure the same way any secured lender does: through advance rates, or haircuts, where the lender advances less than 100% of the loan amount to maintain a margin of protection, and through concentration limits that cap how much of a facility can be tied up in a particular loan type, geography, or borrower profile. Both mechanisms exist because the warehouse lender is carrying the loan as collateral for the period it sits on the line, and its own risk exposure rises the longer that dwell period runs. A shorter, more predictable dwell period is not just a benefit to the originator. It is also a lower-risk position for the warehouse lender itself, which is part of why dwell time increasingly comes up in warehouse facility negotiations, not just internal cost conversations.

The capital velocity math

Warehouse capacity is not really about how large a line an institution has access to. It is about how many times that capital can turn over in a year.

A representative warehouse line that turns over roughly every 25 days supports somewhere in the range of 14 to 15 full turns of that capital annually. Compress the same cycle down to roughly 10 days, and that same committed capital can turn over closer to 36 times a year, more than double the annual production capacity without adding a dollar of new warehouse capacity. That is the actual lever behind capital velocity: the same balance sheet supporting meaningfully more origination volume, purely by shortening how long each loan sits before it is sold.

Why this is a trust problem, not just an operations problem

Shortening dwell time by making individual steps faster helps only at the margin, because the delay is rarely inside any single step. It is in the handoffs between them, where a buyer, a TPR firm, or a custodian each independently re-verify something a prior participant already confirmed, simply because there is no reliable way to know that verification already happened correctly.

Reducing dwell in a durable way means making certification portable: giving every participant in the chain access to evidence and lineage they can act on directly, instead of asking each one to rebuild their own version of it before the loan can move forward. That is what actually compresses the cycle, rather than just making each individual review a little faster.