Purified terephthalic acid: Correlation
Prices it moves with, and why
PTA is made by oxidising paraxylene with air, using acetic acid as solvent, and is reacted with MEG to make polyester. Most is made and traded in Asia, and margins swing with polyester demand and heavy Chinese capacity.
Proxy US PPI: cyclic intermediate chemicals index (BLS base period) · monthly, Jan 2006 to Sep 2026There is no free public price for purified terephthalic acid itself, so this tab uses the closest public series as a stand-in. Read the numbers as an indication, not as the price of this exact item.
What its price moves with
Selected linkPurified terephthalic acid and Paraxylene
Monthly changes 0.50 moderate correlation 12-month changes 0.73 strong correlation Last 5 years 0.02 monthly changes Lead or lag +1 mo Paraxylene tends to lead by 1 month (r 0.56) Price function, Jan 2006 to Sep 2026 Purified terephthalic acid ≈ 116.6 × (Paraxylene)0.10 R² 0.02 On this fit, a 10% higher paraxylene price goes with a 1.0% higher purified terephthalic acid price over the long run. Units: index (BLS base period) and index (BLS base period). The fit is loose, so treat the function as a rough guide.Chart: Purified terephthalic acid and Paraxylene 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: Purified terephthalic acid price against Paraxylene 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.Paraxylene is nearly all of PTA's raw material cost, so PTA is priced as a processing margin over it. The petrochemical proxy moves with the cyclic proxy at 0.50 monthly and 0.73 yearly, but only 0.02 over the last five years.
moderate co-movement month to month · 249 months Show chartsPolyester plants buy PTA and MEG together in fixed proportions, so the two trade as a pair and share the same demand. The basic organics proxy moves with the cyclic proxy at 0.33 monthly and 0.80 yearly.
weak co-movement month to month · 249 months Show chartsPolyester fibre and filament take most PTA, so textile demand in China, India and elsewhere decides run rates. The fibre index moves with the proxy at 0.14 monthly and 0.68 yearly, a lagged and loose monthly tie.
little or none co-movement month to month · 249 months Show chartsPET bottle resin is the second large outlet, so summer drinks demand and recycling rates affect PTA. The broad resin index moves with the cyclic proxy at 0.38 monthly and 0.73 yearly.
weak co-movement month to month · 249 months Show chartsOil sets the cost of naphtha and so of paraxylene, which flows through to PTA. The tie is moderate, 0.20 monthly and 0.67 yearly, as Chinese capacity additions often decide PTA margins.
little or none co-movement month to month · 249 months Show chartsParaxylene comes from refinery reformers, many of them in integrated Asian complexes, so refinery economics shift PTA costs. The refinery index moves with the cyclic proxy at 0.34 monthly and 0.74 yearly.
weak 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.