Every account starts with four default sleeves: Equities (S&P 500), Bonds (10yr Treasuries), Cash, and Gold. If your portfolio also holds small-caps, international, REITs, TIPS, or any other sleeve the defaults don't cover, use + Add Asset Class inside the account's Allocation modal to bring it in.

Where to find it

Open an account, click the pie-chart Allocation button, and scroll to the bottom of the sleeve list. The dashed purple + Add Asset Class tile opens a picker grouped by Equities, Bonds, and Other (Cash, Gold). Anything already on the account is filtered out so you can't add a duplicate.

What the picker offers

• Real historical series - each option is a deeply-historical, real-data market series (e.g. US Small Blend, International Developed, NAREIT REITs, TIPS). Returns come from the actual data, not a Monte Carlo generator.
• First usable year - some sleeves don't extend back to 1871. The picker shows the first usable year (e.g. International Developed starts in 1990).
• Pre-history proxy - if a series starts after 1871, FIREproof never fabricates earlier years. Instead, pre-history cycle years are held in an acknowledged proxy (e.g. "Pre-1990 → S&P 500 Composite"), and the picker labels the substitution so it's visible.

Stable value and guaranteed fixed accounts

Some retirement-plan options never lose principal: a 401(k) or 403(b) stable value fund, the TSP G Fund, TIAA Traditional, or an insurer's fixed account. Modeling them as Bonds charges them price losses they never take, such as the roughly 12% the 10-year Treasury proxy loses in 2022. The Bonds group of the picker offers two series built for them:

• Stable Value (5-yr avg 10y Treasury) credits the average of the last five January 10-year Treasury yields as interest, every year, with no price change. Use it for stable value funds, the G Fund, and any fixed account whose guaranteed minimum is 2% or less (a minimum that low would almost never have mattered: the average has dipped below 2% only once since 1871, in 2022).
• Guaranteed Fixed Account (3% minimum) is the same rate, never below 3%. Use it for TIAA Traditional RA contracts and other fixed accounts or annuities with a 3% minimum, which older contracts commonly carry. The floor applies in 34 of the 155 years of history, mostly 1937-1958 and 2013-2024.

The rate lags the market. Because each year's rate is a five-year average, it trails changes in interest rates. When rates rise, it credits less than a new 10-year Treasury pays: 11.0% in 1982 against 14.6%, and 2.4% in 2024 against 4.1%. When rates fall, it credits more: 3.9% in 2009 against 2.5%. Real stable value funds behave the same way, which is why they lag bond funds after a rate rise and lead them after a fall.

How they are taxed. The rate is credited as interest each year, not as a change in price. Inside a 401(k), 403(b), IRA or other retirement account that makes no difference: nothing is taxed until you withdraw. In a regular brokerage account, the interest is taxed every year, and the year-by-year view lists it as dividends. FIREproof currently taxes it at the lower qualified-dividend rates, as it does all bond interest, although interest is really ordinary income, so taxes on these series in a brokerage account come out somewhat low.

Asset Class vs. Custom Asset

They look similar but answer different questions:

• + Add Asset Class picks an additional real historical series already in FIREproof's catalog. Use this when the sleeve you hold has long-term data available (small caps, REITs, TIPS, international, etc.).
• + Add Custom Asset creates a Monte Carlo generated sleeve from a mean / volatility / shape you supply. Use this only when the catalog doesn't have what you need (gold tilts beyond the built-in, BTC, private alternatives, a custom equity assumption). Custom assets carry the trade-offs spelled out in Custom asset classes.