FireFolio field guide · No prior knowledge needed
What you own. Why its price moves. What the numbers mean for your future.
Start with a $1,000 loanLesson 01
Stocks make you a part-owner. Bonds make you a lender. A bond fund owns a basket of these loans on your behalf.
The face value in this example.
A 4% fixed coupon, paid annually here.
The principal comes due.
Illustrative bond issued at face value, with no early repayment. Payments depend on the borrower meeting its obligations. Many real bonds pay interest semiannually; some, including Treasury bills, pay no regular coupon and are sold at a discount.
If you hold to maturity and the borrower pays, you receive the contractual face value. If you paid $1,050 to buy it from someone else, maturity still returns $1,000, not $1,050.
You may sell before maturity, but the price can be higher or lower than what you paid.
A conventional bond fund replaces securities as its strategy requires. Your shares do not have their own fixed repayment date. Diversification can reduce exposure to one borrower, but cannot eliminate losses.
An exchange-traded fund (ETF) is one fund wrapper, traded on an exchange. Your retirement account may hold a bond mutual fund or bonds inside a target-date fund instead.
Issuer: the borrower. Principal / face value: the amount contractually due at repayment. Maturity: that repayment date. Default: failing to meet the debt’s payment obligations.
Credit rating: an agency’s opinion of repayment risk. Investment-grade ratings indicate stronger assessed credit quality; below-investment-grade debt is often called high yield. Callable: the issuer can repay early under the bond’s terms, potentially leaving you to reinvest at a lower rate.
Inflation: rising prices that reduce what money buys. Reinvestment risk: future interest or repaid principal may have to be invested at a lower rate. Yield: a rate relating income and/or contractual payments to a price; its exact definition matters.
Lesson 02
Imagine your bond pays $40 a year. If newly available bonds offer a better deal, a buyer needs a lower price to make your old payments competitive.
Try it · one fixed-rate bond
The annual coupon stays $40. Principal stays $1,000. Only the discount rate and remaining term change. Annual discounting; no default, call, accrued interest or trading costs.
-$43.29 versus $1,000 face value
New buyers demand more than your 4% coupon. The price falls below face value.
Effective or modified duration estimates price sensitivity to a small change in yields. Approximate price change (%) = −duration × yield change in percentage points. A move from 4% to 5% is +1 percentage point, or 100 basis points.
These are price-only illustrations for a +1 percentage point parallel yield move, excluding income. Large moves, curve changes, credit spreads, convexity and changing cash flows can make actual results differ. Duration is not a maturity date or a guaranteed recovery time.
FINRA: understanding duration ↗If you must sell, market price matters. Longer duration means greater sensitivity to yield changes. Even a government bond fund can lose money.
Higher rates can improve income as payments and maturing bonds are reinvested. Lower rates can reduce future income. This helps explain why short-term losses and better future yields can happen together; it does not establish a recovery date.
Lesson 03
Use this as a reusable method: identify the loan basket, decode the headline figures, then inspect exposure, costs and structure.
Worked example · IB01
A dated teaching example, not a recommendation. Figures as of 15 October 2026 unless stated. Checked 16 October 2026; not a live feed.
The US government. That answers the borrower question, not whether the fund’s resale price or your home-currency value can fall.
The strategy targets short remaining maturities. It refreshes the basket; your ETF shares do not mature in one year. Short bonds reprice their income relatively quickly as rates change.
Earning income from short-term debt. This marketing phrase does not make an ETF an insured bank deposit or settle whether it fits your spending currency and access needs.
From the lesson to the real screen
These are real, dated screenshots of the same fund. Choose a screen, then a number. The explanations work for similar fields on other services too.
Annotation 1 of 4
On the screen: USD 122.16
Net asset value is assets minus liabilities, divided by shares. This is the value of one fund share at the valuation time.
Your broker uses an exchange price, which can differ. $122.16 is not a bond’s face value or evidence that the fund is expensive.
Decode the headline numbers →Use the issuer documents to confirm the share class and methodology, then check the date, currency and definition of each field. These snapshots do not establish a synchronized price comparison.
Try this with a fund you own: find it on the issuer’s website and another service. Match the exact share class, identify one differently named field, then explain why you would or would not compare the two values.
Choose a figure to learn what it can actually tell you.
Net asset value: the fund’s assets minus liabilities, divided by its shares. This is the calculated value of one ETF share, in USD, at the valuation time.
Bond valuations, income earned, expenses, and distributions change NAV. Accumulated income stays inside this share class.
This is neither a bond’s face value nor a guaranteed broker price. A $122 ETF is not inherently more expensive than a $20 ETF. Compare exposures and percentage costs.
Ten shares represent $1,221.60 at this NAV. The actual purchase uses the exchange ask price, plus any broker fees.
Coupon: the contractual interest rate on a bond’s face value. It ignores what you paid. Current yield: annual coupon divided by today’s price; it ignores the gain or loss on repayment.
Yield to maturity (YTM): the discount rate that equates the purchase price with contractual cash flows. Receiving all payments is assumed; realizing that compounded return also depends on coupon reinvestment. A fund’s weighted YTM is not your locked-in return.
Yield to worst: the lowest yield across relevant contractual maturity and early-call scenarios. It does not include every possible loss from default. Distribution yield: a payout-based measure, often backward-looking. 30-day SEC yield: a standardized US fund-income measure, generally after fund expenses. Check dates, fee treatment and definitions before comparing.
Start with exposure and costs. Open any row for why it matters and a question to ask of another fund.
17 facts shown
Who owes the money? “Fixed income” describes debt; it does not promise a fixed fund price. Sovereign, corporate, municipal, and mortgage debt have different repayment risks.
Read the holdings and credit breakdown. Several Treasury securities still share one sovereign borrower.
Maturity measures time to repayment; duration estimates sensitivity to market yields. They are not interchangeable. A duration of 0.32 suggests about a 0.32% price decline for a one-percentage-point yield rise.
Match the timing to your spending needs. A short average can hide longer holdings; inspect the distribution. Duration is only a local approximation.
Base currency is fund accounting; share-class currency is its reporting denomination; trading currency is what you pay on an exchange. Underlying currency exposure and explicit hedging determine exchange-rate risk.
Buying a local-currency listing does not itself hedge foreign assets. Check “Hedged” and the prospectus; hedges have costs and can be imperfect.
The index describes the strategy the fund tries to follow. Its borrower, currency, maturity and inclusion rules explain what you own and when holdings change.
Compare funds with similar benchmarks first. A higher-yield corporate fund is not a like-for-like alternative to a Treasury fund.
Income stays in the fund rather than being paid out to you. A distributing share class pays cash and normally sees NAV fall by that payment, all else equal.
Compare total returns. Accumulation does not make income tax-free; account type and local rules determine tax treatment.
The recurring fund charge is reflected in NAV. At a constant $10,000 holding, 0.07% is about $7 a year. It is not a separate $7 bill.
Broker fees, spreads, currency conversion and taxes can sit outside TER. Published NAV returns already reflect ongoing fund expenses; do not deduct TER again.
The fund can earn revenue by lending securities against collateral. That may offset some costs but introduces borrower and collateral risk.
This is a historical figure for the provider’s reporting period, not a guaranteed rebate. Do not add it again to reported total return or assume TER minus this number is your future cost.
Share-class assets are one slice; whole-fund assets include other share classes. Scale can help operating viability, but does not guarantee liquidity or investment quality.
Do not add these overlapping figures. Inspect bid–ask spreads and underlying-bond liquidity, not size alone.
The number of shares in the class. ETF creations and redemptions can change it. NAV multiplied by shares is approximately the class’s assets, allowing for rounding.
More shares does not mean a higher return. Share issuance accompanied by assets is not the same as a company issuing shares to raise spending money.
A share class and its parent fund can start on different dates. Dates tell you how much actual performance history exists.
Ask which rate and credit environments that history covers. A longer history is context, not evidence that future losses are impossible.
The fund’s legal home. This differs from where its bonds were issued, where it trades, and where you pay tax.
Check broker access and tax treatment for your residence and account. The UK product page is not an indication that this fund suits every country’s retirement account.
A European regulated fund framework with rules governing fund operations and investor protection.
It is not deposit insurance, a capital guarantee, or universal account eligibility. Read the risk document for the exact share class.
Physical means the strategy holds securities; sampled means it uses a representative selection rather than necessarily every index constituent.
Inspect tracking difference, holdings and permitted derivatives. “Physical” does not mean the fund never lends securities or uses derivatives.
The portfolio is adjusted to keep following the strategy. As bonds age or mature, the basket is refreshed.
Monthly rebalancing does not mean monthly cash payments. A 0–1 year fund keeps rolling; it does not promise to give your original investment back after one year.
The ISIN identifies this security/share class. Tickers depend on the exchange. Similar fund names can hide different income or hedging policies.
Match the ISIN, share class, exchange and trading currency in your broker before comparing figures.
A sustainability-disclosure classification. iShares uses “Other” for products outside its Article 8 and Article 9 categories.
This is neither a credit rating nor a safety score. Use the underlying disclosures if sustainability characteristics matter to you.
The manager operates the strategy; the custodian safeguards assets; the administrator handles fund records and calculations.
These identify who does what and where to investigate operational issues. Recognizable names do not remove market or counterparty risk.
Lesson 04
For a short holding period, buying, selling and converting currency can cost more than the fund’s annual charge.
Try it · a constant $10,000 holding
0.17% per year, simple annualized cost equivalent.
No market return assumed. Constant balance and same spread at entry/exit; half the spread each way. FX applies twice only if you convert both ways. Excludes tax, platform fees, internal transaction costs and changes in premium/discount. This is cost arithmetic, not a return forecast.
TER/OCF or expense ratio reduces fund value over time. Portfolio transaction costs and hedging effects also matter. Tracking difference compares the fund’s realized return with its benchmark; it already reflects multiple effects, so do not simply add it to TER.
The bid is what a buyer offers; the ask is what a seller wants. Their gap is the spread. Check broker commission, custody/platform charges, currency conversion and market price versus NAV. A premium that disappears before you sell can reduce your return.
Individual bonds may have dealer markups/markdowns and minimum purchase sizes rather than a fund expense ratio. The quoted “clean” price may exclude accrued interest. Accrued interest compensates the seller for interest earned since the last coupon; it is part of settlement, not an extra management fee.
Compare after-tax outcomes only with the rules for your country, account and security. Income, capital gains, inflation adjustments and accumulated fund income can receive different treatment. This educator does not calculate tax or assume the UK example is eligible in your account.
Lesson 05
A higher yield may mean more risk, a different currency, or a longer wait. First decide when you need the money and which surprises you can absorb.
| Option | What it can help with | What to investigate |
|---|---|---|
| Cash / insured savings | Near-term payments and ready access. | Inflation, variable interest, withdrawal rules and local insurance limits. |
| Money market fund | A fund of very short-term instruments. | Credit and liquidity risk, changing income and fees. It is not an insured bank account. |
| Individual high-quality bond | A contractual payment schedule for a known date. | Issuer, maturity, purchase price, call terms, inflation and resale costs. |
| Short-duration bond fund | Diversified bond exposure with lower rate sensitivity than a comparable longer-duration fund. | Credit and FX risk still matter. Income resets as holdings roll; no guaranteed final value. |
| Intermediate / long bond fund | Longer exposure to rates; a possible component of a diversified portfolio. | Larger price swings. Government and corporate versions have very different credit risks. |
| High-yield corporate bonds | Income from riskier borrowers. | Default and recovery risk; spreads can widen during the same stress that hurts stocks. |
| Inflation-linked bonds | Payments linked to a specified inflation index. | Real-yield sensitivity, index rules, tax and maturity. A fund can still fall in price. |
| Stocks / stock funds | Long-term participation in business growth. | Large drawdowns, uncertain dividends and no promised maturity payment. |
Hold a bond maturing around the date you need the money, allowing time for settlement.
Repayment is face value, not necessarily your purchase price, and depends on the issuer paying. Selling early exposes you to market prices. Inflation and opportunity cost remain.
Compare with a suitable insured deposit or term deposit in the spending currency, including access restrictions and local protection limits.
Line up the same holding period and spending currency, then compare borrower type, credit quality, duration, maturity mix, currency hedging, income policy and total costs. Check whether either fund uses leverage, derivatives or callable debt. Compare the same kind of yield on the same date and total returns over the same period.
For example, a hypothetical 6% corporate fund with duration 7 and a 4% Treasury fund with duration 0.3 differ in both credit risk and rate sensitivity. Their yields alone cannot tell you which fits next year’s spending.
One easily missed comparison · currency
Assume an unhedged asset earns 4% in USD over one year. Change the value of USD in your spending currency.
(1 + asset return) × (1 + currency change) − 1
Hypothetical 4% return, not IB01’s forecast or YTM. No fees, tax or hedging. Exchange-rate movement is separate from the broker’s FX conversion fee.
Lesson 06
You do not need to predict every rate decision. Watch the risks that could interfere with the job you gave your money.
A rise in relevant market yields usually reduces existing fixed-rate bond prices.
Reinvested money can earn more after a rise; after cuts, income can decline. A central-bank announcement is not a one-for-one move in every bond yield.
A spread is extra yield over a comparable government bond. Wider spreads can hurt corporate prices even if government yields fall.
Watch issuer finances, downgrades and concentration. High yield can come with meaningful default losses; ratings are opinions, not promises.
Inflation surprises can affect market yields and prices.
Fixed payments may buy less. Inflation-linked bonds respond to their specified inflation index, but can fall when real yields rise.
Foreign exchange moves can outweigh a short bond’s interest income.
Use the currency of future spending as your reference. Hedging reduces some currency risk, with costs and imperfect results.
Selling urgently can mean a wider spread or an ETF price below NAV.
Watch persistent changes in trading conditions and fund viability. On-screen trading volume alone misses underlying-market liquidity.
A distribution is a transfer out of NAV, not free additional return.
Review duration, credit mix, fees and index changes. A rising payout or yield can signal changed risk rather than an improved investment.
Your first exercise · use a fund you already own
No trade needed. Find these answers, one at a time. Your progress lasts for this visit.
0 of 5 explored. Missing information is a useful question for the plan provider.
A spending date gets closer, your cash needs change, the fund changes strategy, or its duration and credit mix drift from your expectations. Daily price movement alone does not tell you to trade.
What a bond selloff means for FIRE →
Explore the ETF comparison tool →
Price-history comparisons do not replace a factsheet check of duration, credit and yield definitions.
