How Diversification Protects Goals With Deadlines

A goal with a deadline, such as tuition due in five years or a house deposit in three, turns risk into a narrower question: how likely is the money to be short on that date, and by how much? Volatility describes the journey; a deadline cares about the balance at the end. Spreading money across assets that do not move in lockstep reduces the swings, and matching each slice of money to the date it is needed limits how much of the goal is exposed when markets fall shortly before that date.

Key takeaways

Over 1928–2025, all-stock holdings ended 26.5% of single years below their starting value, 11.7% of 5-year periods and 5.6% of 10-year periods, yet the worst 10-year period still lost 32.0% after inflation.
Treasury bills never lost money in nominal terms, yet after inflation they ended 44.8% to 48.3% of 3-, 5- and 10-year periods behind where they started.
On a hypothetical $40,000 held for five years, moving from all stocks to Treasury bills historically gave up about $26,500 of median outcome and raised the worst result by about $19,800, both in nominal dollars.
A mix that shifted to Treasury bills for the final two years of a 10-year goal had no losses in those two years in any of 89 periods, against 13 for all stocks, at the cost of a lower median.
Target date funds and 529 age-based portfolios automate this shift, but the SEC notes that funds with the same target date can follow different glide paths and that target date funds do not guarantee income.

Deadline risk is not volatility

Volatility, the standard deviation of returns, says how widely results scatter around their average. A dated goal fails when the balance on the date falls below what is needed: shortfall risk. A. D. Roy's 1952 paper "Safety First and the Holding of Assets" framed portfolio choice around minimizing the chance of ending below a "disaster" level, and the SEC's beginners' guide to asset allocation describes the aim in similar terms: a mix with the highest probability of meeting the goal at a level of risk the investor can live with.

Two things set the threshold: the amount needed, fixed in dollars (a deposit in a contract) or tied to prices (tuition or living costs that rise with inflation), and the growth required to get there:

r = (G / P)^(1 / n) − 1

r = annual growth needed
G = amount needed on the deadline
P = amount set aside today
n = years until the deadline

Illustrative example: $36,000 set aside for a $40,000 deposit due in 3 years needs (40,000 / 36,000)^(1/3) − 1 ≈ 3.57% a year. If the full $40,000 is already saved, r is zero and the only job is not to lose any of it. The same portfolio can be risky for the first saver and comfortable for the second.

What 1928–2025 windows show

The table counts rolling periods (1928–1930, 1929–1931 and so on) using Aswath Damodaran's annual return data for the S&P 500 with dividends (back-filled with earlier large-company indexes before 1957), the 10-year Treasury bond and the 3-month Treasury bill, and December-to-December changes in the BLS consumer price index (CPI-U) for the real figures. "60/40" means 60% stocks and 40% 10-year Treasuries, rebalanced every year. Fees and taxes are ignored. The periods overlap, so the 89 ten-year windows contain only 9 non-overlapping decades: the counts describe one US history, not independent trials, and they are not forecasts.

Period length	Holding	Ended below start, nominal	Ended below start, after inflation	Worst period, nominal	Worst period, after inflation
3 years (96 periods)	All stocks	15.6%	20.8%	−61.6% (1930–1932)	−54.8% (1929–1931)
3 years	60/40	9.4%	26.0%	−39.0% (1929–1931)	−29.5% (1972–1974)
3 years	T-bills	0%	44.8%	+0.1% (2013–2015)	−22.9% (1946–1948)
5 years (94 periods)	All stocks	11.7%	23.4%	−49.3% (1928–1932)	−41.8% (1937–1941)
5 years	60/40	4.3%	11.7%	−24.1% (1928–1932)	−24.3% (1937–1941)
5 years	T-bills	0%	46.8%	+0.3% (2011–2015)	−26.6% (1942–1946)
10 years (89 periods)	All stocks	5.6%	12.4%	−15.5% (1929–1938)	−32.0% (1999–2008)
10 years	60/40	0%	11.2%	+19.5% (1929–1938)	−23.6% (1972–1981)
10 years	T-bills	0%	48.3%	+1.9% (1934–1943)	−40.2% (1941–1950)

The share of losing periods for stocks fell from 26.5% of single calendar years to 5.6% of 10-year periods because average gains piled up over more years, not because outcomes became predictable. The dollar spread widened: on $10,000 in stocks, the middle 80% of results ran from $8,897 to $13,228 after 1 year and from $13,661 to $47,573 after 10 years. The worst cases stayed severe at short horizons: a 3-year all-stock holding once lost more than 60%. Treasury bills protected nominal dollars but lost purchasing power in close to half of all periods, worst in the 1940s, when inflation outran bill rates.

The 60/40 row shows what diversifying across stocks and bonds did here: it never finished a 10-year period with fewer nominal dollars, and it cut the share of 5-year periods with a nominal loss from 11.7% to 4.3%. It did not remove inflation risk; over 3 years its real loss rate was higher than that of stocks (26.0% against 20.8%).

The price of cutting shortfall risk

Lowering the chance of a shortfall usually means accepting a lower typical outcome. The table prices that trade-off for a hypothetical $40,000 held for 5 years across the same 94 periods. The 10th percentile is the result that 9 in 10 periods matched or beat.

Holding	Median, nominal	10th percentile, nominal	Worst, nominal	Median, after inflation	10th percentile, after inflation	Worst, after inflation
All stocks	$72,337	$39,143	$20,266	$59,938	$33,963	$23,276
60/40	$61,558	$45,988	$30,360	$51,270	$38,028	$30,296
T-bills	$45,802	$40,422	$40,112	$40,440	$34,643	$29,378

Moving from all stocks to Treasury bills gave up $26,535 of median outcome and raised the worst nominal result by $19,846. Against 60/40, bills lifted the worst nominal outcome by $9,752, but 60/40 had the higher 10th percentile in both nominal and real terms and a similar real worst case. Bills bought protection against the extreme nominal tail, not a better result in most bad periods.

Illustrative example: a deposit due in 3 years

The saver with $36,000 who needs $40,000 in 3 years, across all 96 historical 3-year periods:

All stocks fell short in 20 periods (20.8%), missing by $9,296 on average; the worst outcome was $13,831.
60/40 also fell short in 20 periods, missing by $4,986 on average; the worst outcome was $21,946.
T-bills fell short in 55 periods (57.3%), but missed by only $2,537 on average; the worst outcome was $36,050.

The bill result depended heavily on the interest-rate era: they missed in 30 of 31 periods starting 1928–1958, 5 of 32 starting 1959–1990 and 20 of 33 starting 1991–2023. Frequent small misses and rare large ones are different risks, which a shortfall probability alone hides. When the required rate exceeds safe yields, the other levers are the amount saved, the date and the size of the goal.

Matching money to the date

Liability matching means holding money needed in a given year in instruments that mature close to it, so the amount available does not depend on market prices that day. A "bucket" structure applies this to a series of dates: near-term spending in short instruments, middle years in securities maturing then, and money not needed for a decade or more in a diversified mix with time to recover from a fall. The SEC's guide calls a change in time horizon the most common reason for changing an allocation.

2022 shows why maturity matters. In Damodaran's data, the 10-year Treasury bond returned −17.8% as yields rose, while 3-month bills earned 2.1%. Money needed within a year and held in a long bond fell with it; money held in bills maturing before the deadline did not.

Where dated money can sit

Treasury bills and notes. Bills mature in 4, 6, 8, 13, 17, 26 or 52 weeks and notes in 2, 3, 5, 7 or 10 years, paying face value at maturity. They can be sold earlier at the market price. All Treasury marketable securities are backed by the full faith and credit of the US government.
Certificates of deposit. The FDIC insures deposits up to $250,000 per depositor, per FDIC-insured bank, for each account ownership category; deposits in one category at one bank are added together. The SEC's CD guide says the terms should state the maturity date and any early-withdrawal penalty, and names inflation outpacing the CD's rate as the main risk.
Series I savings bonds. Their rate combines a fixed rate with an inflation rate reset every 6 months. They earn interest for 30 years rather than maturing near a goal, so they fit a deadline by being cashed in: not during the first 12 months, and with the last 3 months of interest forfeited before 5 years. Electronic purchases are capped at $10,000 per Social Security number per calendar year.

The SEC guide adds a distinction that is easy to miss: putting a house deposit entirely in cash equivalents can be a reasonable allocation under certain circumstances, but it does not diversify. Matching sets how much risk each slice of money carries; diversification within the longer-dated slice is what keeps that risk from resting on a few holdings.

The emergency fund: a deadline of "any day"

An emergency fund has the least predictable deadline. The CFPB's guide to building an emergency fund defines it as a cash reserve for unplanned expenses or emergencies, says the amount depends on the household's situation, and stresses keeping it safe and accessible. With no known date, it cannot be matched to a maturity.

Glide paths in funds and 529s

A glide path is a schedule that moves money from stocks toward bonds and cash as a date approaches. The SEC's investor bulletin on target date funds (March 2025) describes two kinds. A "to" glide path stops shifting at the target date; a "through" glide path keeps shifting past it. "To" funds typically turn conservative earlier, so at many points they hold lower-risk, lower-return investments than "through" funds. The bulletin also states that these funds "do not guarantee that you will have sufficient retirement income, or a specific level of retirement income, at or after the target date."

The SEC's introduction to 529 plans (January 2026) describes the same idea in college savings: age-based portfolios typically shift into more conservative investments as the beneficiary nears college age, while static portfolios keep the same mix. States do not guarantee education savings plan investments, and money in them can be lost.

Illustrative example: a 10-year goal with yearly deposits

Assume $5,000 is added at the start of each year for 10 years ($50,000 in total), tested over all 89 historical 10-year periods. The glide path holds 80% stocks and 20% 10-year Treasuries in years 1–5, 60/40 in years 6–8 and only T-bills in years 9–10. The real column treats each deposit as $5,000 of constant purchasing power.

Approach	Median balance	10th percentile	Worst balance	Periods below $50,000 after inflation	Periods with a loss in the final 2 years	Largest final-2-year loss
All stocks throughout	$93,459	$62,334	$41,133 (1999–2008)	11 of 89	13 of 89	$29,958 (2001–2002)
60/40 throughout	$79,032	$65,496	$52,130 (1965–1974)	9 of 89	14 of 89	$13,321 (1973–1974)
Glide path	$75,143	$59,868	$52,157 (1934–1943)	14 of 89	0 of 89	None

The glide path had the lowest median, trailed 60/40 at the 10th percentile and matched its worst result. What it changed was the final stretch: after the switch to bills the balance never dropped in dollar terms, while all stocks lost $29,958 in its worst final two years. The cost was inflation risk: more periods ended below $50,000 in real terms. Without deposits or withdrawals, the order of returns would not change a fixed mix's final balance; de-risking late matters because the most money is at stake near the end, with no time left to make up a loss.

Frequently asked questions

Are Treasury bills covered by FDIC insurance?

No. The FDIC lists Treasury bills, bonds and notes among the products it does not insure, alongside stocks, mutual funds and annuities. Treasuries are backed by the US government directly, a different protection from deposit insurance; a CD is a bank deposit and falls under the FDIC limits.

Do target date funds with the same year hold the same mix?

Not necessarily. The SEC's bulletin says funds with the same target date may follow different strategies and glide paths, shift to conservative holdings at different times or rates, and charge different fees. Because these funds often invest in other funds, fees can be charged at both levels. The SEC suggests reading the prospectus and most recent shareholder report.

How often can the investments in a 529 plan be changed?

According to the SEC's 529 bulletin, current tax law allows an account holder to change the investment option in an education savings plan twice per year, or when the beneficiary changes. That limits manual moves toward a nearer deadline; age-based portfolios shift automatically.

Are brokered CDs different from CDs bought at a bank?

Brokered CDs are sold by brokerage firms or independent "deposit brokers" rather than by the bank itself. The SEC notes that deposit brokers are not licensed or certified and that no state or federal agency approves them, and it advises checking the background of the issuer or deposit broker. The FDIC, for its part, notes that its insurance covers only deposits, and only at FDIC-insured banks, so coverage depends on the bank that issued the CD.

Do the historical figures include fees and taxes?

No. The series are the S&P 500 with dividends, a 10-year Treasury bond repriced each year at a constant 10-year maturity, and each year's average 3-month bill rate, all before fund fees, trading costs and taxes. Actual accounts would have ended lower by their costs.

Questions to ask about a goal

When is the money needed? Write down the date, or the series of dates for goals paid over several years, such as four years of tuition.
How much is needed, and in what terms? Fixed in dollars or rising with prices decides whether nominal or real shortfall matters more.
What growth does it require? Compute r = (G / P)^(1/n) − 1 and compare it with the yields on Treasuries maturing near the deadline, published in Treasury's daily yield curve rates.
How flexible is the date? A retirement date that can move by a year allows more market exposure than a closing date set in a contract.
What happens if it falls short? Name the fallback (borrowing, delaying, a smaller goal) and the largest miss it can absorb.
Which money is matched to which date? List what matures before each deadline and what stays exposed to markets; for a target date fund or 529 age-based portfolio, check its own schedule.

The site's Investment Growth calculator shows how a balance grows at assumed rates, and the Rebalancing calculator shows the trades needed to reach a new mix.