FRM Exam Part II · The Failure Mechanics of Dealer Banks

Case Studies: Bear Stearns and Lehman Brothers Failure Mechanics

Updated 11 October 2026 · Fact-checked

Bear Stearns and Lehman failed because dealer banks funded long, illiquid assets with short-term secured and unsecured funding. Bear lost repo funding and prime brokerage clients in days in March 2008. Lehman lost counterparties' confidence in September 2008. Both saw their liquidity pools drain as collateral demands and withdrawals rose.

Understand Case Studies: Bear Stearns and Lehman Brothers

A dealer bank holds large trading inventories and funds them mostly with short-term borrowing, chiefly repo (secured borrowing against collateral). It also relies on prime brokerage balances, where hedge fund clients leave cash and securities with the dealer. Both funding sources can leave quickly.

To survive a run, the dealer holds a liquidity pool of cash and highly liquid assets. The pool is useful only if it is unencumbered, meaning not already pledged, and if it is large relative to the outflows in a stress. A pool that looks big on paper can vanish fast when counterparties demand more collateral or refuse to roll funding.

Bear Stearns (March 2008). Rumours about its mortgage exposure spread in the week of 10 March. Repo lenders stopped rolling funding, even on some collateral, and hedge fund clients withdrew prime brokerage balances. Its liquidity pool fell from about USD 18 billion to very little within days. The Federal Reserve supported the sale to JPMorgan Chase through a loan against assets. The key point: a run by secured lenders and clients can destroy a dealer within days, even when it reports solid capital.

Lehman Brothers (September 2008). Lehman had large real estate and leveraged exposures and weak earnings. Confidence fell through the summer. In the week of 8 September, counterparties asked for more collateral, clearing banks wanted more margin, and clients pulled balances. Lehman filed for Chapter 11 on 15 September 2008, with no buyer and no government rescue. Derivatives counterparties then closed out positions, and customers' assets held in the UK affiliate were frozen. The key point: the failure was a loss of counterparty confidence, with collateral calls and trapped assets making the liquidity drain worse.

Compare them. Both were liquidity runs on highly levered dealers. Bear's run was fast and ended in an assisted sale. Lehman's was a slower loss of confidence ending in a disorderly bankruptcy. The Lehman failure spread losses through the OTC derivatives and money markets, and led to resolution and clearing reforms.

Key formulas to remember

Leverage ratio (simple): Leverage = Total assets ÷ Equity; Higher leverage means a small asset fall wipes out equity. Dealers ran very high leverage before 2008.
Liquidity pool adequacy: Survival horizon = Liquidity pool ÷ Daily net stressed outflow; Use unencumbered, liquid assets after haircuts. This is a simple approximation, not a regulatory formula.
Haircut and funding: Cash raised = Market value of collateral × (1 − haircut); Higher haircuts in a stress mean less cash per unit of collateral, so the dealer must fund the gap.
Equity wipe-out: Asset fall that wipes out equity = 1 ÷ Leverage; At 30 times leverage, a fall of about 3.3% in asset value eliminates equity.

How to solve Case Studies: Bear Stearns and Lehman Brothers questions

Use this order for any question on dealer bank failure cases.

1Identify the firm and date: Bear Stearns (March 2008) or Lehman (September 2008).
2Name the funding channels at risk: repo, prime brokerage balances, unsecured funding, derivative collateral.
3Check the liquidity pool: is it unencumbered, how big, and how quickly did it fall?
4Identify the trigger: loss of confidence, higher haircuts or margin, collateral calls, client withdrawals.
5Describe the outcome: assisted sale for Bear, Chapter 11 and disorderly close-out for Lehman.
6Link to the lesson: runs on secured funding, collateral dynamics, resolution and policy reforms.
7If numbers are given, compute leverage, haircut cash or survival horizon, then interpret.

Quickest way: Run-or-solvency check

When to use it: When a multiple-choice question asks what caused or distinguished a failure.

Ask: was the main driver a funding run or a capital loss? In both cases, answer a run on funding with capital doubts.
Ask: was there a rescue? Bear yes (sale to JPMorgan with Fed support), Lehman no (bankruptcy).
Ask: which channel? Repo and prime brokerage point to the dealer-bank mechanism.
Eliminate options that say the pool was ample or that the failure was only due to trading losses.

Common mistakes in Case Studies: Bear Stearns and Lehman Brothers

Saying Lehman was rescued like Bear Stearns.
Both are grouped as 2008 failures.
Fix: Remember Bear was sold to JPMorgan with Fed support; Lehman filed for Chapter 11.
Treating the liquidity pool as a fixed safe buffer.
The reported balance looks large.
Fix: Check whether assets are unencumbered and how quickly stressed outflows can drain them.
Thinking repo is safe because it is secured.
Collateral seems to remove risk.
Fix: Lenders can raise haircuts or refuse to roll. Secured funding can still run.
Ignoring prime brokerage and clients.
Focus stays on wholesale lenders.
Fix: Hedge fund clients withdrawing cash and securities was a key outflow, especially at Bear.
Blaming only asset losses for the failures.
Mortgage losses dominate the story.
Fix: Losses started doubts, but the failures came through funding and collateral runs on highly levered balance sheets.

Worked examples

Example 1

A dealer has total assets of USD 400 billion and equity of USD 10 billion. By what percentage must asset value fall to eliminate equity? Interpret.

Show the solution

Leverage = 400 ÷ 10 = 40.
Wipe-out fall = 1 ÷ 40 = 0.025.
That is 2.5%.

Answer: A 2.5% fall in asset value eliminates equity. Such leverage means small losses or doubts can trigger a run.

Example 2

A dealer's unencumbered liquidity pool is USD 18 billion. In a stress, daily net outflows are USD 6 billion from repo and clients. How long does the pool last, and what does this show?

Show the solution

Survival horizon = 18 ÷ 6.
= 3 days.

Answer: The pool lasts about 3 days. This matches a Bear-type run, where a seemingly large pool disappeared within days. It shows that pool size must be judged against stressed outflows.

Exam tips

Know the dates and outcomes: Bear in March 2008 (assisted sale), Lehman on 15 September 2008 (Chapter 11).
Expect questions comparing the two: speed, rescue, and the spread of losses through derivatives and clients.
Focus on mechanisms: repo runs, haircuts, collateral calls, prime brokerage withdrawals, and unencumbered liquidity.
Pick answers that tie the failure to funding structure, not only to asset losses.

Practice questions from The Failure Mechanics of Dealer Banks

Case Studies: Bear Stearns and Lehman Brothers: frequently asked questions

What is the main difference between the Bear Stearns and Lehman failures?

Bear Stearns suffered a rapid funding run and was sold to JPMorgan Chase with Federal Reserve support. Lehman suffered a loss of counterparty confidence and filed for Chapter 11 without a rescue. Lehman's failure also caused wider disruption through derivatives and client assets.

What is the liquidity pool in the Bear Stearns case?

It was the stock of cash and liquid, unencumbered assets the firm held to meet outflows. It fell sharply within days as repo lenders and prime brokerage clients withdrew. It shows that a pool must cover stressed outflows.

Why did secured repo funding fail if it was backed by collateral?

Lenders can refuse to roll funding or demand higher haircuts, especially for less liquid collateral. This reduces the cash the dealer can raise. Secured funding therefore still carries run risk.

Does FRM Part II examine this as a case or as concepts?

Expect applied questions on the mechanics: funding channels, collateral dynamics, and policy lessons. Learn the facts as a framework, not as a story.