On May 20, 2008, the Baltic Dry Index — the most-watched freight-rate index in the world — closed at 11,793, an all-time record. Within seven months, by December 5, 2008, the same index had fallen to 663. From peak to trough, the cost of moving a ton of iron ore or coal or grain across an ocean had collapsed by approximately 94 percent.

The fall was not gradual. The index lost half its value in the eight weeks between mid-September and mid-November 2008 — coinciding precisely with the Lehman Brothers collapse and the global credit freeze that followed. There is no comparable peak-to-trough move in any major financial index over a comparable window in the modern era.

The S&P 500 lost 38 percent that year; oil lost 75 percent; the BDI lost 94 percent. The reason is structural: dry-bulk shipping rates are determined by the gap between vessel supply (which is fixed in the short run because new ships take 2-3 years to build) and cargo demand (which can collapse in weeks during a credit shock).