Correlation Analysis
Apple Inc. vs Western Digital Corp.
AAPL vs WDC
+0.629
Moderate positive
When one moves up, the other tends to follow.
Apple Inc.
↗AAPL
Apple is among the largest companies in the world, with a broad portfolio of hardware and software products targeted at consumers and businesses. Apple's iPhone makes up a majority of the firm sales, and Apple's other products like Mac, iPad, and Watch are designed around the iPhone as the focal point of an expansive software ecosystem. Apple has progressively worked to add new applications, like streaming video, subscription bundles, and augmented reality. The firm designs its own software and semiconductors while working with subcontractors like Foxconn and TSMC to build its products and chips. Slightly less than half of Apple's sales come directly through its flagship stores, with a majority of sales coming indirectly through partnerships and distribution.
Market cap 3.8T
Western Digital Corp.
↗WDC
Western Digital is a leading vertically integrated supplier of hard disk drives. The HDD market is a practical duopoly, with Western Digital and Seagate being the two largest players. Western Digital designs and manufactures its HDDs, with much of the manufacturing and workforce located in Asia. The primary consumers of HDDs are data centers.
Market cap 103.1B · 40,000 employees
Time Series
Rebased to 100
Who Moves First
AAPL leads WDC by 6 days
AAPL tends to move before WDC.
Best correlation after shifting: +0.632 (13 shifts scanned)
Do They Crash Together?
Correlation by Market Regime
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
+0.103
11 periods · Return correlation when both series rose
Both Falling
+0.892
7 periods · Return correlation when both series fell
Diverging
-0.474
17 periods · Return correlation when series moved apart
R-Squared
39.6%
Share of variance in one series explained by the other.
Trend Agreement
63.5%
How often both series moved in the same direction period-to-period.
Overlap Quality
1,254
Deep shared window — 1,254 usable pairs.
Significance
p < 0.001
95% CI: [0.595, 0.661]
Scatter
XY Regression
Pipeline
Data quality details
Pipeline
Data quality details
Pipeline Summary
1,254 paired observations survived the daily window.
Raw input
1,254
1,254
Normalized
1,254
1,254
Prepared
1,254
1,254
Aligned
1,254
1,254
Invalid removed
0
A: 0 / B: 0
Duplicates removed
0
A: 0 / B: 0
Alignment drops
0
A: 0 / B: 0
Series A
Apple Inc.
AAPL
Market cap 3.8T
Stock · 1,254 raw → 1,254 prepared
Series B
Western Digital Corp.
WDC
Market cap 103.1B · 40,000 employees
Stock · 1,254 raw → 1,254 prepared
Sign agreement
100.0%
How often both values share the same sign.
Zero crossings
36
Estimated crossover points between normalized spreads.
Slope
0.8088
Linear regression slope.
Intercept
-81.5049
Linear regression intercept.
Related Extremes
Highest and Lowest Correlated
Saved 3 hours ago · ID: stock-aapl-vs-stock-wdc-daily-20260408-qn7s62