Base metals

What does thirty years of bilateral trade data tell us about world trade in base metals? Who makes it, who buys it, which HS6 lines dominate, and how complex is it on average? HS Section 15is one of 21 top-level groupings in the Harmonized Commodity Description and Coding System maintained by the World Customs Organization (WCO, Harmonized System Nomenclature, 2022 edition; HS92 applied here for back-compatibility with 1995 trade).

Who produces it, who buys it

Exporter concentration reflects where productive capacity sits in this section. Comparing the exporter table with the importer table reads as a dependency map: where the gap is large, the section is geographically separated between producers and consumers.

Which HS6 lines lead the section

HS Sections are coarse. Within this section, the 10 largest HS6 lines reveal what is actually being traded — whether the growth comes from a few dominant lines or a broad basket.

Complexity of the section

The Product Complexity Index (PCI) of Hausmann & Hidalgo (2009) scores each HS6 by the productive knowledge its exporters collectively hold. Averaging PCI within an HS section gives a rough read on how sophisticated that corner of the trade system is. PCI is zero-centered; positive sections sit above the world average.

Which economies specialise in this section

Balassa’s (1965) Revealed Comparative Advantage answers the complementary question to “who is biggest”: who is disproportionately specialised in this section relative to its own total export basket and the world’s. Section-level RCA = (X_c,sec / X_c,total) / (X_W,sec / X_W,total). Values above 1 mean the country exports a larger share of its basket in this section than the world does; above 2 is the conventional “strongly specialised” threshold. The sample is restricted to economies with at least US$1B of total exports in 2024 so micro-states with 100% single-section baskets don’t dominate the top.

Supply concentration over time

Whether productive capacity in base metals is concentrating into fewer national hands or spreading across more is the section-level analogue of the DOJ/FTC industry-concentration question (DOJ/FTC Merger Guidelines, 2023). The Herfindahl-Hirschman index of exporter shares within HS Section 15, computed annually, summarises that trajectory in a single line. On the 0–10,000 scale, HHI > 2,500 is the conventional “highly concentrated” threshold and HHI > 1,500 is “moderately concentrated”; 10,000/HHI is the effective number of equally-sized national suppliers. A rising HHI is consolidation; a falling HHI is the entry of new national producers (China in textiles, machinery, and electronics through the 2000s).

Leaders-followers rank change, 2000 vs 2024

Sectoral league-table positions move — sometimes quietly over decades, sometimes sharply around a single policy episode (China’s WTO accession in 2001, the ATC phase-out in 2005, the US-China tariff war of 2018–20). Ranking each exporter in base metalsin 2000 and in 2024 and taking the difference surfaces the countries that have climbed or fallen the furthest in global competitive position. Δ > 0 = climbed the league (improved rank), Δ < 0 = fell.