SeriesMagCorrOverlapThrough
These move together about 62% of the time
Very strong positive
Strong enough to use as a signal — read the stability and regime notes below before relying on it.
Berkshire Hathaway is a holding company with a wide array of subsidiaries engaged in diverse activities. The firm's core business segment is insurance, run primarily through Geico, Berkshire Hathaway Reinsurance Group, and Berkshire Hathaway Primary Group. Berkshire has used the excess cash thrown off from its operations to acquire Burlington Northern Santa Fe (railroad), Berkshire Hathaway Energy (utilities and energy distributors), and the companies that make up its manufacturing, service, and retailing operations (which include Precision Castparts, Lubrizol, Clayton Homes, Marmon, and IMC/ISCAR). The conglomerate is unique in that it is run on a completely decentralized basis. Berkshire i
Market cap 1T · 387,800 employees
State Street SPDR Portfolio S&P 500 Growth ETF
SPYG
What to Watch
Unusual right now
Recent correlation (-48%) is 3.4σ from the long-run average of +87% — pair is behaving differently than usual.
Tighter in drawdowns
Pair moves more tightly when both fall (+60%) than when both rise (+37%) — typical risk-off behaviour.
Regime-dependent
The correlation has flipped sign across time windows — not reliable as a standalone signal.
Time Series
Time-Shifted Correlation
See how correlation changes when one series is offset in time. A taller bar at a non-zero shift means the two move together better when one leads the other — that's a potential lead/lag signal.
Correlation by shift
Click a bar to inspect. Range: -6 to 6 days.
Selected shift
No shift
Correlation at this shift
+87%
No shift — both series at their actual dates.
1,255 overlapping points at this shift
Time series with State Street SPDR Portfolio S&P 500 Growth ETF at original dates
Indexed to 100 at start
Deep Dive
Stability
How the correlation evolves over time. A stable line means the relationship is reliable; large swings signal regime-dependent behavior.
Corr
+87%
Pearson correlation
95% CI
+86% → +89%
Likely range
R²
76.6%
Variance explained
Trend agreement
61.9%
Same-direction moves
Significance
p < 0.001
Statistical confidence
Data points
1,255
Deep
Pipeline
Pipeline Summary
1,255 paired data points survived the daily window.
Raw input
1,255
1,255
Normalized
1,255
1,255
Prepared
1,255
1,255
Aligned
1,255
1,255
Invalid removed
Explore
The strongest positive and inverse pairs we’ve saved for each side of this comparison — good jumping-off points if this result raised a question.
Do They Crash Together?
How these series behave when markets are rising, falling, or diverging. A correlation that holds in drawdowns is very different from one that only works in rallies.
Both Rising
+37%
98 periods · Return correlation when both series rose
Both Falling
+60%
75 periods · Return correlation when both series fell
Diverging
-63%
76 periods · Return correlation when series moved apart
Scatter
0
A: 0 / B: 0
Duplicates removed
0
A: 0 / B: 0
Alignment drops
0
A: 0 / B: 0
Series A
BERKSHIRE HATHAWAY Class B
BRK.B
Market cap 1T · 387,800 employees
Stock · 1,255 raw → 1,255 prepared
Series B
State Street SPDR Portfolio S&P 500 Growth ETF
SPYG
Stock · 1,255 raw → 1,255 prepared
Sign agreement
100.0%
How often both values share the same sign.
Zero crossings
3
Estimated crossover points between normalized spreads.
Slope
0.1821
Linear regression slope.
Intercept
3.8835
Linear regression intercept.
Saved 2 hours ago · ID: stock-brk.b_stock-spyg_5y
SPYG
State Street SPDR Portfolio S&P 500 Growth ETF
Strongest positive