CAPE Ratio (Shiller PE10): S&P 500 Cyclically Adjusted Valuation Since 1881

This dataset compiles the monthly CAPE (Shiller PE10) series from Robert Shiller’s Yale dataset (ie_data.xls), spanning January 1881 to the present — over 1,740 observations covering 145 years of US equity valuation history.

Dataset: S&P 500 Cyclically Adjusted Price-to-Earnings Ratio (1881–2026) · Updated 2026-07-01

Source: Robert Shiller, Yale University — ie_data.xls, open academic data on long-term US equity valuation

Macro Takeaway

Dataset Overview

Dataset Variables

The CSV and Excel files contain the following columns.

Column names match the CSV headers exactly.

Download the Complete Dataset

The full dataset is available in CSV and Excel formats.

Direct CSV Access — Eco3min Structured Dataset

https://eco3min.fr/dataset/sp500-cape-ratio.csv

This URL returns the complete dataset in CSV format. It can be used directly in pandas, R, curl, or any data tool.

Using the Dataset in Python

import pandas as pd

url = "https://eco3min.fr/dataset/sp500-cape-ratio.csv"
df = pd.read_csv(url, parse_dates=["date"])

print(df.head())
print(df.describe())

Using the Dataset in R

library(readr)

url <- "https://eco3min.fr/dataset/sp500-cape-ratio.csv"
df <- read_csv(url)

head(df)
summary(df)

Both examples load the dataset directly from the URL — no download or API key required.

Methodology

The CAPE ratio (cyclically adjusted price-to-earnings ratio, also called Shiller PE10) is computed as the inflation-adjusted S&P 500 price divided by the trailing ten-year average of inflation-adjusted S&P 500 earnings. Both the price series and the earnings series are deflated using the CPI-U index. The ten-year averaging window smooths the cyclical volatility of corporate earnings, producing a more stable valuation gauge than the trailing one-year P/E. On what elevated valuations imply for entering the market, see our reading of investing at all-time highs.

The source dataset is maintained by Robert Shiller (Yale University) in the file ie_data.xls, published as open academic data on Shiller’s personal website. The file aggregates S&P 500 historical earnings reconstructed from Cowles Commission tabulations for the pre-1957 period and from S&P/Standard Statistics for the modern period, alongside the official CPI-U deflator series. Shiller updates the file approximately monthly, typically within the first two weeks of each calendar month. On choosing between near-identical S&P 500 funds, see comparing S&P 500 funds on the details that matter.

Eco3min mirrors the Shiller dataset via an automated pipeline that reformats the source spreadsheet into a normalized CSV/XLSX schema. The dataset is refreshed when a new release is detected at the Shiller source.

Data Quality & Provider Notes

The CAPE ratio dataset is sourced directly from Robert Shiller’s Yale University publication — the canonical academic reference for long-term US equity valuation. The series is not available on FRED; users must work from Shiller’s source file or a mirror such as Eco3min, multpl.com, or commercial data providers.

• Release latency. Shiller updates ie_data.xls on an approximately monthly cadence, generally during the first or second week of each calendar month. The release schedule is informal — there is no fixed publication date or pre-announced calendar — so the latest available observation may lag the current month by two to six weeks.
• Revisions policy. The CAPE ratio is constructed from historical S&P 500 price, dividend, and earnings series plus CPI deflators. Revisions are uncommon but occur when (i) S&P revises historical reported earnings, (ii) the BLS revises CPI back-history during periodic rebenchmarking, or (iii) Shiller corrects historical reconstruction errors flagged by academic readers. Recent observations (current and prior two months) carry slightly higher revision risk than older data.
• Alternative sources. multpl.com and GuruFocus publish derived CAPE series using the same Shiller methodology and inputs. Bloomberg and Refinitiv distribute calculated CAPE values within their valuation toolkits. Some commercial providers compute CAPE with proprietary earnings reconstructions that produce values differing from Shiller’s by 1–3 points — these are not interchangeable for academic citation.
• Known gaps. The series is continuous monthly from January 1881. There are no missing observations, but pre-1926 earnings rely on Cowles Commission historical reconstructions and should be interpreted with awareness that nineteenth-century US accounting practices differed substantially from modern GAAP.

Before running historical analyses, confirm the last observation date against Shiller’s source page directly. For research requiring strict vintage reproducibility, archive the source ie_data.xls at the date of analysis — Shiller does not publish a vintage history.

Common Pitfalls When Using the CAPE Ratio

The CAPE ratio is widely cited in equity valuation analysis, but several recurring interpretation errors distort its signal.

1. Confusing CAPE with trailing or forward P/E. The CAPE ratio uses a ten-year inflation-adjusted earnings average; trailing P/E uses the most recent twelve months of nominal earnings; forward P/E uses analyst consensus estimates of the next twelve months. The three metrics produce systematically different readings, particularly near cyclical inflection points where trailing earnings collapse (P/E spikes mechanically) while the CAPE ratio remains anchored by its smoothing window.
2. Reading absolute CAPE levels without regime context. A CAPE ratio reading of 30 in 1999 reflected a different macro regime than a reading of 30 in 2025: real interest rates, corporate tax rates, accounting standards, and the composition of the S&P 500 have all shifted materially. Comparing absolute levels across decades without controlling for these factors overstates valuation comparability.
3. Ignoring accounting and composition shifts in the earnings denominator. The ten-year earnings average is sensitive to one-time accounting events that compress reported earnings — notably the 2001 goodwill write-downs under FAS 142, the 2008 financial-crisis loss recognitions, and the structural shift in S&P 500 sector composition toward asset-light technology issuers (where reported earnings understate economic earnings due to intangibles expensing). Each of these distortions inflates the CAPE ratio mechanically without reflecting a “real” valuation increase.
4. Confusing the CAPE ratio with the Excess CAPE Yield. The CAPE ratio is an absolute valuation level; the Excess CAPE Yield is the CAPE earnings yield (1/CAPE) minus the 10-year real Treasury yield, designed as an equity-bond relative-value indicator. The two metrics can diverge sharply: in regimes of deeply negative real rates, the Excess CAPE Yield can remain elevated even as the CAPE ratio itself sits near historical extremes.
5. Source confusion. CAPE ratio readings differ across providers because some commercial vendors reconstruct historical earnings using methodologies that diverge from Shiller’s original inputs. This Eco3min dataset mirrors Shiller’s ie_data.xls verbatim and is therefore directly comparable to published academic research; values quoted from Bloomberg, FactSet, or other providers may differ by 1–3 points and should not be substituted in citation without verifying the source.

Historical Regimes

1881–1928 — Pre-Depression cycles. The CAPE ratio fluctuated between approximately 5 and 25 over forty-seven years, reflecting the volatile earnings cycle of an industrializing US economy. Repeated banking panics (1873, 1893, 1907) drove the metric to single-digit troughs.

September 1929 — Pre-crash peak. The CAPE ratio reached approximately 32.6 — at the time, the highest reading in the available series. The metric would not return to that level for another seventy years.

June 1932 — Depression trough. Following the most violent equity drawdown in US history, the CAPE ratio fell to approximately 5.6, an all-time low. The reading reflected both collapsed prices and persistently depressed ten-year earnings averages.

1933–1965 — Postwar expansion. The CAPE ratio rose gradually from single digits to approximately 24 by January 1966, supported by stable corporate earnings growth and declining bond yields. The 1966 peak represented an early example of late-cycle equity valuation pressure.

1966–1982 — Stagflation compression. The CAPE ratio declined from 24 to approximately 7 over sixteen years, as accelerating inflation eroded real earnings and rising 10-year Treasury yields compressed equity multiples. The July 1982 trough at 6.6 coincided with the start of a multi-decade disinflation rally.

1982–March 2000 — Disinflation rally and dot-com peak. The CAPE ratio rose from below 7 to a record 44.2 in December 1999 — the highest reading in the 145-year history of the series. This peak surpassed even the 1929 extreme and remains the all-time high. The dataset spans this peak and its aftermath in monthly resolution, providing the canonical empirical reference for late-bubble equity valuation analysis. Common misreadings of this history are addressed in the recurring misconceptions about valuations and bubbles.

2000–2009 — Two crashes. The dot-com unwind drove the CAPE ratio from 44 to 21 by September 2002. After a partial recovery, the 2008–2009 global financial crisis pushed the metric to approximately 13.3 in March 2009 — the lowest reading since 1986.

2010–2021 — ZIRP-fueled re-rating. Persistently low real interest rates supported a sustained CAPE ratio expansion from 13 to above 38 by November 2021. The 2021 peak ranked as the second-highest reading in the series, exceeded only by the December 1999 dot-com extreme. The macro logic — that low real rates structurally support high valuations — is examined in the CAPE-vs-real-rates study.

2022–2026 — Rates reset and recovery. The 2022 duration shock compressed the CAPE ratio to approximately 27 by October 2022, before the metric rebounded above 35 through 2024–2025 as AI-driven mega-cap earnings revisions reinflated the ten-year smoothed average. Triangulated with the trailing P/E and the Excess CAPE Yield provides the cleanest read of valuation regime through the current cycle.

Related Macroeconomic Datasets

The CAPE ratio sits at the intersection of equity valuation and real-rate analysis. The datasets below provide the complementary inputs — alternative valuation metrics, real-rate context, and equity return histories — needed to interpret CAPE readings within a complete macro-financial frame.

Macroeconomic Dataset Hub

This dataset is part of the Eco3min macro-financial data repository.

Sources

• Robert Shiller, Yale University — ie_data.xls, open academic data on long-term US equity valuation
• Shiller, R. J. (2000, updated edition 2015). Irrational Exuberance. Princeton University Press — methodological reference for the CAPE ratio construction

Dataset Reference