Finance-Theory · Unit 5 · Video 1 · Interactive Practice

Fixed Income: The $61.2 Trillion Market Where Treasuries Replaced Mortgages

IKey Formulas

Formula	Name	What it says
$V_0 = \sum_{t=1}^{T} \dfrac{\text{CF}_t}{(1+r)^t}$	Value of a fixed-income security	Every $\text{CF}_t$ is a promised amount on a fixed date; with default and uncertainty set aside, present value prices it
$\text{share}_i = \dfrac{x_i}{\sum_j x_j}$	Sector share	A sector's figure over the total of the same measure: $6{,}400.4 / 26{,}732.2 \approx 24\%$ of 2006 debt outstanding
$\dfrac{dA}{dt} = \text{issuance} - \text{repayments}$	Stock and flow	$A$ , the amount outstanding, is a level at a date; issuance is new debt per year, and it changes $A$ only by its excess over debt repaid
$\dfrac{61.2}{160.7} \approx 38.1\%$	U.S. share of world fixed income, 2025	Both are amounts outstanding, in trillions; one third of 160.7 is about 53.6, so the U.S. is well over a third

Key Insight: In each period the stock and the flow name the same leader: mortgage-related debt in 2006 (24% of the amount outstanding, 34% of issuance) and Treasuries today (about $31.8 trillion outstanding in August 2026, $4.8 trillion issued in 2025). Government borrowing now sets the pace.

IISizing the $61.2 Trillion

How much of the world's $160.7 trillion of fixed income is American?

IIIStock and Flow, 2006 and Today

The amount outstanding is a stock and issuance a flow, and in each period both name the same leader.

IVQuiz Questions

Problem 1 · The Rest of the World

Given: worldwide fixed income outstanding in 2025 was $160.7 trillion, and U.S. fixed income outstanding was $61.2 trillion — find the share of the world's fixed income that is not American.

✅ Correct! The world total already includes the U.S., so the rest is

160.7 - 61.2 = 99.5

trillion, and

99.5 / 160.7 \approx 61.9\%

❌ That is the U.S. share.

61.2 / 160.7 \approx 38.1\%

answers the opposite question; what lies outside the U.S. is

100\% - 38.1\% = 61.9\%

❌ The U.S. is counted twice, and this is its own share.

61.2 / (61.2 + 160.7) = 61.2 / 221.9 \approx 27.6\%

treats the worldwide figure as if it excluded the U.S., and even on that reading it measures the American part, not the rest. $160.7 trillion is the whole world, America included, so the rest is

99.5 / 160.7 \approx 61.9\%

❌ The U.S. is counted twice.

160.7 / 221.9 \approx 72.4\%

treats $160.7 trillion as the rest of the world and adds the U.S. on top. The worldwide figure already contains the American $61.2 trillion.

Show solution

The worldwide figure already includes the United States, so the rest of the world is the difference:

160.7 - 61.2 = 99.5 \ \text{trillion}

As a share of the world total:

\frac{99.5}{160.7} \approx 0.619 = 61.9\%

Check: the U.S. share is $61.2 / 160.7 \approx 38.1\%$ , and $38.1\% + 61.9\% = 100\%$ ✓. The American market alone is well over a third of the world's; everyone else together holds a little under two thirds.

Problem 2 · Larger by How Much?

Given: at the end of 2006, mortgage-related debt outstanding was $6,400.4 billion (24% of the market) and Treasury debt outstanding was $4,283.8 billion (16%) — find by what percent mortgage-related debt was larger than the entire Treasury market.

✅ Correct!

6{,}400.4 / 4{,}283.8 \approx 1.494

, so mortgage-related debt was about 49.4% larger, and the rounded shares agree:

24 / 16 = 1.5

❌ That is a gap in percentage points.

24\% - 16\% = 8

points of the whole market. Measured against the Treasury market's own size, the gap is

2{,}116.6 / 4{,}283.8 \approx 49.4\%

❌ Wrong base.

2{,}116.6 / 6{,}400.4 \approx 33.1\%

says how much smaller Treasury debt was than mortgage-related debt. "Larger than the Treasury market" puts the Treasury amount in the denominator.

❌ That is the ratio, not the increase.

6{,}400.4 / 4{,}283.8 \approx 1.494

means mortgage-related debt was 149.4% of the Treasury market, which is 49.4% more than it.

Show solution

Step 1 — the gap in billions.

6{,}400.4 - 4{,}283.8 = 2{,}116.6

Step 2 — the gap relative to the Treasury market, the thing being compared against:

\frac{2{,}116.6}{4{,}283.8} \approx 0.494 = 49.4\%

Equivalently, $\dfrac{6{,}400.4}{4{,}283.8} \approx 1.494$ and $1.494 - 1 = 0.494$ .

Check with the shares: both amounts are shares of the same total, $26{,}732.2$ billion, so their ratio equals the ratio of the shares. The rounded shares give $24/16 = 1.5$ , about 50% larger, which matches once the rounding is allowed for. The 8-point gap between 24% and 16% is a difference in percentage points of the whole market, not a percent of the Treasury market.

Problem 3 · Last Year's Flow and Treasury's Share

Given: U.S. long-term fixed-income issuance in 2025 was $11.5 trillion, up 9.7% on the year, and the Treasury brought $4.8 trillion of it to market.

What was long-term issuance in 2024?

What share of 2025 long-term issuance was Treasury debt?

✅ Correct! 2024 issuance was

11.5 / 1.097 \approx 10.48

trillion, and the Treasury's $4.8 trillion is

4.8 / 11.5 \approx 41.7\%

of the 2025 flow.

❌ 9.7% of the wrong year. The rise is 9.7% of the 2024 amount, so undo it by dividing:

11.5 / 1.097 \approx 10.48

. Multiplying by

1 - 0.097

takes 9.7% of the 2025 amount instead:

11.5 \times 0.903 \approx 10.38

❌ That grows 2025 by another 9.7%.

11.5 \times 1.097 \approx 12.6

looks forward a year. The $11.5 trillion is already the grown figure; divide by

1.097

to go back.

❌ That is 9.7% of the 2025 amount, not a level.

11.5 \times 0.097 \approx 1.1

measures a rise, and on the wrong base. The question asks for the 2024 total:

11.5 / 1.097 \approx 10.48

❌ That divides a flow by a stock.

4.8 / 61.2 \approx 7.8\%

sets one year's new Treasury debt against the whole amount outstanding. A share of 2025 issuance divides by 2025 issuance, $11.5 trillion.

❌ That divides by 2024's total.

4.8 / 10.48 \approx 45.8\%

mixes two years. The Treasury's 2025 issuance is a share of 2025 issuance.

❌ That divides by the sum of the rounded sector figures. The six sector figures add to only about

11.40

trillion, and

4.8 / 11.40 \approx 42.1\%

. The sector figures are rounded and do not add exactly to the total; the stated total is $11.5 trillion.

Show solution

Step 1 — undo the growth. "Up 9.7% on the year" means $I_{2025} = I_{2024} \times (1 + 0.097)$ , so

I_{2024} = \frac{11.5}{1.097} \approx 10.48 \ \text{trillion} \approx 10.5 \ \text{trillion}

Check: $10.48 \times 1.097 \approx 11.50$ ✓. Multiplying $11.5$ by $0.903$ instead would take 9.7% of the new amount off, giving $10.38$ , which is too small.

Step 2 — the Treasury's share of the same flow. Numerator and denominator are both 2025 issuance:

\frac{4.8}{11.5} \approx 0.417 = 41.7\%

Two denominators are tempting and wrong: $61.2 trillion is the amount outstanding, a stock, not a year's issuance; and the six sector figures, $4.8 + 2.2 + 1.9 + 1.4 + 0.5873 + 0.5174 \approx 11.40$ , are rounded and fall short of the stated $11.5 trillion total.

Problem 4 · Placing New Instruments

Given: two securities the video does not name — (1) a finance company pools thousands of equipment leases and sells claims on their payments; (2) the Government of Canada issues a bond. Place each one.

The equipment-lease pool: which of the 2006 data's seven sectors?

The Canadian government bond: which of the six standard categories?

✅ Correct! A pool of any non-mortgage asset sold as claims is asset-backed, and the Treasury category includes foreign government equivalents such as Bunds, JGBs and gilts.

❌ Same structure, different collateral. Mortgage-related securities are specifically claims on pools of mortgages. A pool of leases is asset-backed, and the data counts the two separately.

❌ Look at what the claims are on. The seller is a company, but investors hold claims on the payments of a pool of leases, not the company's own bonds or notes. Pooled non-mortgage assets form the asset-backed sector.

❌ Money markets are short-term paper. That sector holds short-term instruments such as commercial paper; claims sold on the payments of a pool of non-mortgage assets are what the data counts as asset-backed.

❌ An agency is not the government itself. Federal agency securities are issued by federal agencies and government-sponsored entities such as the Federal Home Loan Banks, Fannie Mae and Freddie Mac. A bond of the national government itself is a Treasury equivalent.

❌ Municipal means state and local. Municipal securities are issued by state and local governments. Canada's national government issues the foreign equivalent of a Treasury.

❌ The issuer is a government, not a company. A national government's bond belongs with Treasuries and their foreign equivalents.

Show solution

The equipment-lease pool → Asset-backed. Asset-backed securities can be backed by any asset; the video's examples are credit card receivables, auto loans and student loans, and a pool of leases works the same way: the pool's payments feed claims that are sold to investors. Mortgage-related securities share that structure but are specifically about mortgages, and the data counts the two as separate sectors.

The Canadian government bond → Treasury. The Treasury category holds U.S. Treasury bills, notes and bonds together with their foreign equivalents: German Bunds, Japanese government bonds, British gilts. A bond of Canada's national government is one more such equivalent. Federal agency securities come from U.S. federal agencies and government-sponsored entities, municipal securities from state and local governments, and corporate securities from companies.

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