Dry bulk shipping (iron ore, coal, grain, and other unpackaged commodities, tracked broadly by indices like the Baltic Dry Index) and container shipping are structurally different markets that happen to share the same ocean, and their rates frequently diverge rather than move together.
Container rates are driven heavily by consumer and manufactured-goods demand, retail inventory cycles, and the alliance capacity-management dynamics already discussed — a relatively small number of large carriers managing supply across standardized routes. Dry bulk is driven by industrial commodity demand (steel production, power generation, agricultural trade), has a much more fragmented ownership structure, and reacts faster to single-commodity demand shocks like a change in Chinese steel output or a poor grain harvest.
For most China-origin importers of manufactured or consumer goods, dry bulk indices are not directly relevant to their own freight costs — the relevance is more that container shipping occasionally gets described in the general press using commodity-market language that does not actually apply to how liner shipping rates are set, which is worth being able to distinguish when reading industry news.
The one place crossover genuinely matters is vessel capacity: shipyards building new dry bulk and new container tonnage compete for the same construction slots and raw steel inputs, so a boom in one segment's newbuild orders can indirectly affect delivery timelines in the other.