Electric motors and drives: Correlation
Prices it moves with, and why
Motor prices rest on copper or aluminium windings, electrical steel, rare-earth magnets in high-efficiency designs, and factory labour. Demand comes from pumps, fans, compressors, industry and vehicles. The index also covers generators, so it tracks electrical machinery broadly.
Price index US PPI: motors, generators, motor generator sets index · monthly, Jan 2006 to Sep 2026What its price moves with
Selected linkElectric motors and drives and Copper
Monthly changes -0.01 little or none correlation 12-month changes -0.07 little or none correlation Last 5 years -0.23 monthly changes Lead or lag +3 mo Copper tends to lead by 3 months (r 0.10) Price function, Jan 2006 to Sep 2026 Electric motors and drives ≈ 5.84 × (Copper)0.41 R² 0.33 On this fit, a 10% higher copper price goes with a 4.0% higher electric motors and drives price over the long run. Units: index and $/mt.Chart: Electric motors and drives and Copper prices rebased to 100 at Jan 2006, log scale
Both prices rebased to 100 at Jan 2006, on a log scale so equal percentage moves look the same size.Chart: Electric motors and drives price against Copper price, monthly, log scales, with fitted line
Each dot is one month; paler dots are older (2006), darker dots recent (2026); the ringed dot is the latest month. The dashed line is the fitted price function. Both axes are logarithmic.Copper windings are one of the largest material costs in a motor. Yet the index barely follows copper, with correlations close to zero, because makers apply metal surcharges and long contracts instead of moving list prices with each copper swing.
little or none co-movement month to month · 249 months Show chartsMotor cores are stacks of thin electrical steel sheet. Yearly moves correlate at 0.21 with the steel index, a weak link because electrical steel is a specialised grade with limited suppliers, and the general steel index does not track it closely.
little or none co-movement month to month · 249 months Show chartsPermanent-magnet motors in electric cars, drones and efficient pumps use neodymium magnets. China controls most rare earth supply, so export rules can raise costs and push makers toward magnet-free designs. Rare earths have no price series here.
Not enough overlapping price history to measure.Variable-speed drives and inverters control most modern motors, so the two are often sold together. Monthly moves correlate at 0.26 and yearly at 0.77, a common driver from electrical equipment costs and industrial investment.
weak co-movement month to month · 249 months Show chartsGearboxes and couplings connect motors to pumps, conveyors and machines and are ordered together. Yearly moves correlate at 0.86 and monthly at 0.27, which reflects shared US machinery costs and the same capital spending cycle.
weak co-movement month to month · 249 months Show chartsWindings are impregnated with epoxy and other resins for insulation. This is a small input, and monthly moves correlate at only 0.02, though yearly moves correlate at 0.57 as both follow wider US industrial price trends.
little or none co-movement month to month · 249 months Show chartsHow to read these numbers
Correlation of monthly changes (the number in the coloured pill) compares how much each price moved, month by month, since 2006 or the first month both series exist. It runs from −1 to +1: near +1 the two usually rise and fall in the same months, near 0 there is no link, and a negative number means they tend to move in opposite directions. Above 0.7 is strong, 0.4 to 0.7 moderate, 0.2 to 0.4 weak.
12-month changes compare year-on-year moves, which shows whether two prices share the same cycles even when the month-to-month noise differs.
Price function is a straight-line fit of the two prices on logarithmic scales: price ≈ k × (partner price)β. β is how much this price moves, in per cent, for a 1% move in the partner over the whole period, and R² is the share of the variation the fit explains. Two prices that both drift up with inflation can fit well without any real link, so read it together with the monthly correlation.
Lead or lag checks whether the monthly correlation is clearly higher when one price is shifted by 1 to 6 months.
Correlation is not cause. The reasons on each card explain the economic link; the numbers show how strongly it has shown up in prices. Proxy series are US producer price indexes or related prices and can blur the real link.
Data: World Bank Commodity Price Data (Pink Sheet), October 2026; US Bureau of Labor Statistics producer price indexes, IMF primary commodity prices and US EIA prices via FRED, Federal Reserve Bank of St. Louis, retrieved November 2026. Calculations by this site.