Guide

Quantitative easing explained

Harbor Credit Union's asset-liability committee met every FOMC week with one model: map the federal funds rate decision to net interest margin. When the Fed cut to the zero lower bound in March 2020, the model said margins had bottomed. Instead, the Fed announced unlimited Treasury and agency MBS purchases — quantitative easing (QE) — and the 10-year yield fell from 1.15% to 0.54% in three weeks while the policy rate stayed at zero. Mortgage refi volume doubled; the bond portfolio marked up $41 million; duration risk the ALM desk thought was capped suddenly expanded. The rate tool and the balance-sheet tool are not the same lever.

Quantitative easing is unconventional monetary policy where a central bank creates reserves and uses them to buy long-duration assets — typically government bonds and sometimes mortgage-backed securities or corporate debt. The goal is to ease financial conditions when short-term rates are already near zero, compress term premia, support credit markets, and signal commitment to recovery. This guide covers QE mechanics, program types, transmission channels, how QE differs from rate cuts, the unwind via quantitative tightening (QT), portfolio and macro implications, the Harbor Credit Union ALM refactor, a technique decision table, pitfalls, and an investor checklist.

What QE is — and what it is not

QE is large-scale asset purchases (LSAPs) funded by central-bank money creation. The Fed (or ECB, BOJ, BOE) buys securities from banks and primary dealers; payment credits bank reserve accounts at the central bank. The seller often reinvests proceeds into other assets, pushing investors out the risk spectrum.

QE is not:

Direct government spending. The Treasury still issues debt; the Fed buys it in secondary markets (with legal limits on monetization).
The same as cutting the policy rate. Rate cuts hit the front end of the curve immediately; QE primarily targets longer yields and balance-sheet conditions.
Permanent money printing for households. Most reserves stay inside the banking system unless lent or spent through credit creation.
Guaranteed asset inflation. QE eases conditions; risk assets still depend on earnings, risk appetite, and timing.

Balance sheet mechanics

Track three line items on the central bank's balance sheet:

Account	QE impact	Why it matters
Securities held	Rises as purchases accumulate	Duration and reinvestment risk sit on the central bank's books
Reserve balances	Rises as sellers are paid	Abundant reserves era — fed funds trades near IORB corridor
Liabilities (currency, TGA, RRP)	Offsetting flows vary	Treasury General Account drains can tighten liquidity despite QE

In the U.S., the Fed's SOMA portfolio holds Treasuries and agency MBS. Purchases are conducted at market prices; the Fed does not set a yield cap unless it explicitly adopts yield curve control (as Japan has at times). Reinvestment policy matters: maturing bonds can be rolled into new purchases or allowed to run off — the difference between ongoing QE and passive balance-sheet normalization.

Program taxonomy

Not all QE programs target the same markets. Classify announcements by asset class and intent:

Program type	Typical assets	Primary goal
Treasury LSAP	2y–30y nominal Treasuries	Lower long yields, flatten or control curve shape
Agency MBS QE	Fannie/Freddie/Ginnie pass-throughs	Compress mortgage spreads, support housing credit
Credit facilities	Corporate bonds, ETFs, ABS (emergency)	Restore market function when liquidity vanishes (e.g. 2020 SMCCF)
Foreign swap lines	FX liquidity to other central banks	Dollar funding stress relief globally
Yield curve control	Pin specific maturity yield	Cap long rates without announcing purchase size (BOJ history)

The composition of purchases shifts transmission. MBS QE directly affects primary mortgage rates via the option-adjusted spread channel; Treasury-heavy QE moves the yield curve and term premium more broadly. Emergency credit facilities are often smaller but psychologically powerful — they backstop market plumbing when dealers refuse to intermediate.

Transmission channels

Economists debate which channel dominates; in practice several operate together:

Portfolio balance. The central bank removes duration from private hands; investors rebid remaining bonds at lower yields or buy riskier substitutes (credit, equities).
Signaling. Open-ended QE communicates “lower for longer” beyond what forward guidance alone achieves — especially when the policy rate is stuck at zero.
Liquidity and market function. During stress, dealer balance sheets are the binding constraint; Fed purchases clear inventory and restart price discovery.
Wealth and collateral. Higher bond and home prices raise household net worth and collateral values, supporting consumption and lending — with lag and distributional skew.
Exchange rate (international). Easier U.S. financial conditions can weaken the dollar, boosting exports and imported inflation — relevant for global portfolios.

Transmission is not instantaneous. Credit spreads may tighten within days; mortgage refi waves take months; broad M2 growth depends on bank lending appetite, not reserves alone. That lag is why markets often front-run QE announcements and fade them if economic data disappoints.

QE vs rate cuts — when each tool is used

Dimension	Policy rate cut	Quantitative easing
Curve target	Front end (overnight → 2y)	Belly and long end, credit spreads
Typical regime	Normal policy space above zero	Often at or near zero lower bound
Reversal speed	Can hike quickly if inflation surprises	Balance sheet unwind (QT) is slower and politically visible
Bank NIM effect	Compresses deposit-loan spread quickly	Can steepen curve if long yields fall less than front end — or flatten if long end collapses

Central banks often sequence tools: cut rates first, add forward guidance, then launch QE if conditions remain tight. In 2020 the Fed used all three within weeks. Investors who model only the policy rate miss the second and third waves.

Quantitative tightening — the unwind

Quantitative tightening (QT) shrinks the balance sheet by allowing maturities to roll off without reinvestment (passive QT) or by active sales (rare in modern Fed practice). QT removes reserves and lets long-duration supply return to private markets, tending to lift term premia and long yields — even if the policy rate is unchanged.

QT interacts with fiscal flows: heavy Treasury issuance plus Fed runoff increases duration supply to the market simultaneously — a “double supply” story that weighed on bonds in 2022–2023. Conversely, pausing QT while the Treasury rebuilds the TGA can confuse liquidity analysis. Track net liquidity: reserves + reverse repo usage + TGA balance, not QE headlines alone.

Harbor Credit Union ALM refactor

After the 2020 QE shock, Harbor Credit Union rebuilt its rate-risk playbook in three layers:

Dual-track monitoring. Fed funds path and SOMA weekly change + 10y yield + mortgage spread dashboard — not one model.
Duration buckets by scenario. Base (no QE), easing (QE restart), tightening (QT acceleration) with separate OCI stress for the AFS portfolio.
Refi convexity overlay. MBS QE accelerates prepayments; the desk added negative convexity limits on agency MBS holdings and shifted some duration hedging to Treasury futures.

Result: when the Fed restarted balance-sheet expansion in stress episodes, NIM forecasts stopped treating zero rates as “no more easing.” The lesson generalizes beyond banks — any duration-heavy portfolio needs a QE/QT scenario, not just a dot plot.

Technique decision table

Market question	Start here	Also consider
Will the Fed ease at the next meeting?	Fed funds futures + FOMC statement	Balance sheet footnotes, MBS reinvestment language
Why did long yields fall with no rate cut?	QE announcement or flow data	Flight-to-quality, growth scare, foreign buying
Is liquidity tightening despite dovish rhetoric?	TGA build + QT pace + RRP drain	Bank reserves vs LCR constraints
How does easing reach stocks?	Lower discount rate + tighter credit spreads	Risk appetite, earnings cycle (QE is not sufficient alone)
Inflation after QE?	Credit growth + fiscal impulse + supply shocks	M2 velocity, not M2 level alone

Common pitfalls

Equating reserves with inflation. Idle reserves do not buy goods; lending and fiscal policy mediate the link.
Ignoring composition. Treasury-only QE moves different markets than MBS-heavy programs.
Static duration models. Prepayment speeds change when QE compresses mortgage rates — MBS duration is path-dependent.
Assuming symmetry. QT does not perfectly reverse QE price effects; term premia can stay elevated after runoff.
Headline chasing. Markets price expected purchase pace; “unlimited” wording matters less than weekly settlement amounts.
Single-country lens. ECB or BOJ QE shifts global bond demand and FX — U.S.-only models miss spillovers.

Production checklist

Monitor policy rate and balance sheet weekly change (H.4.1 release).
Track purchase composition: Treasuries vs MBS vs emergency facilities.
Model three scenarios: status quo, QE restart, QT acceleration.
Include TGA and reverse repo in net liquidity view.
Stress-test duration with prepayment-sensitive MBS paths.
Read reinvestment policy language in FOMC statements, not just the rate dot plot.
Separate market-function QE (crisis) from cyclical easing when judging persistence.
Document transmission lag assumptions (credit, housing, equities).
Compare term premium estimates before/after major QE announcements.
Review international central bank QE for cross-border flow effects.
Reconcile M2 narratives with bank lending standards (SLOOS).
Maintain runbook for rapid Fed balance-sheet surprises (emergency facilities).

Key takeaways

QE is a balance-sheet tool, not a rate cut by another name. It targets long yields, spreads, and market function when conventional space is exhausted.
Purchase composition determines who benefits. MBS QE hits housing; Treasury QE moves the broader curve.
Transmission runs through portfolios, credit, and expectations — with lags and no guarantee of risk-asset rallies.
QT is the slow unwind. Runoff plus Treasury supply can tighten conditions even with a steady policy rate.
Investors need dual-track models. Harbor Credit Union's mistake — watching only fed funds — is common and expensive.