Investing - Theory, News & General • Re: RIP Ibbotson SBBI data

1.There will be a 100th anniversary edition of the SBBI published in mid-2026. All the series were anchored in December 1925, hence the 100th ‘anniversary’. Elroy Dimson and others will join Roger Ibbotson in that volume.

2.All the data to 20xx (the date of your last purchase whenever that was) remain available (most early errors were corrected long ago). What is lost is the easy availability of the 2024 extension, the 2025 extension, etc.)

3.But that’s not much of a loss: most of the series in the SBBI are available elsewhere (NAREIT, S&P, CRSP). And Siamond makes our life simple by posting an annual update on most of these in convenient downloadable form.

So, there will be no SBBI data for 2024 and later years?

An important SBBI data series was that for intermediate-term government bonds. In the early 1990s, William Bengen used SBBI data to calculate that some portfolios of common stocks and intermediate-term government bonds supported at least 30 years of inflation-adjusted withdrawals for all starting years when the initial withdrawal rate was 4%. The withdrawal rate to a few more digits, was higher for portfolios using intermediate-term government bonds rather than long-term bonds or Treasury Bills.

Hello FactualFran: the new improved successor to the old SBBI is published here: https://rpc.cfainstitute.org/research/f ... nd-returns

All of the old SBBI series are reproduced/continued through 2025, and much more. For bonds, there are now four bills series, 30, 90, 180 and 360 days; 2, 3, 5 and 7 year note series; 10 and 20 year bonds.

The old 5-year series was, ah, a piece of work, with yield curve estimations for the early years, 6- and 7- year bonds pressed into service, even a 50-year bond in its last years. All of the new series are estimated off a single yield curve equation.

The new 5-year series comes in with a lower yield/return and much intra-year variation from the old. The S&P 90 is no longer used prior to 1957. Whether Bengen / Trinity would get the same results I cannot say.

BTW, the new volume is a superset of the old SBBI with broader coverage. I'm one of over a dozen new contributors.

Statistics: Posted by McQ — Wed Oct 07, 2026 9:49 pm