2027: The Transition Year After the High-Price Marker

Goldman Sachs Research described the S&P 500 valuation at roughly 21× earnings and projected 2027 EPS growth of about 13%. The calculator below is intentionally simple: it holds everything else constant and shows the mechanical effect of a change in the earnings multiple.

Formula: (ending P/E ÷ starting P/E) × (1 + EPS growth) − 1. This is a sensitivity calculation, not a market forecast.

Reverse-engineered sequence

A: 1927 → 1945 → 1965 → 1981 → 1999 → 2019 → 2035 → 2053, with intervals 18, 20, 16 repeating: a 54-year supercycle.

B: 1926 → 1935 → 1945 → 1953 → 1962 → 1972 → 1980 → 1989 → 1999 → 2007 → 2016 → 2026 → 2034 → 2043 → 2053, with intervals 9, 10, 8 repeating: a 27-year cycle.

C: 1924 → 1931 → 1942 → 1951 → 1958 → 1969 → 1978 → 1985 → 1996 → 2005 → 2012 → 2023 → 2032 → 2039 → 2050 → 2059, with intervals 7, 11, 9 repeating: another 27-year cycle.

Test result: the sequence is reproducible as calendar arithmetic, but historical alignment does not establish causal or out-of-sample forecasting power. The earlier ClearGlass backtest found the chart more useful as a broad regime hypothesis than as an exact crash-timing system.

High-confidence risk regime: earnings expectations decline while credit spreads widen and unemployment rises. This three-system deterioration is more decision-useful than a single calendar cycle.

Strong constructive regime: inflation falls, policy becomes less restrictive, real GDP remains above roughly 2%, earnings rise, credit stays healthy, and AI productivity becomes measurable.

Bottom line

2027 looks more like a potentially profitable but increasingly selective year than an obvious crash year. The historic chart makes 2026 the important high-price marker; modern evidence says the real test is whether earnings and AI productivity can grow fast enough to justify elevated valuations.

If the answer remains yes, 2027 can extend the expansion. If it turns from yes → no while credit and employment deteriorate, 2027 could become the year the current bull-market regime changes character.

The operational rule is simple: use the old cycle as a prior; use observable evidence as the trigger.

Sources & provenance

• Federal Reserve — June 2026 Summary of Economic Projections: median projections for 2026–2028, including 2027 real GDP, unemployment, PCE, core PCE and federal funds rate. Primary source
• Congressional Budget Office — The Budget and Economic Outlook: 2026 to 2036: 2027 real GDP, labor-market path, inflation path and Treasury-rate outlook. Primary source
• IMF — World Economic Outlook Update, July 2026: global growth, inflation, technology-cycle and geopolitical-risk context; includes the Canada outlook. Primary source
• Goldman Sachs Research — May 28, 2026: S&P 500 EPS projections, valuation commentary and hyperscaler AI-capex estimates. Research source

Retrieved / checked: 2026-08-17. Forecasts are time-sensitive and may be revised. Historical A/B/C dates are treated as a hypothesis from the supplied chart, not as verified economic causality.