The BDI is a summation of a lot of information into a single price point. Megaships, and the general push for more fuel efficiency in new ship builds do impact

The BDI is a summation of a lot of information into a single price point. Megaships, and the general push for more fuel efficiency in new ship builds do impact it to some extent, but not to the degree necessary to account for a major push down. Megaships, in general, don't work for the general shipping case. They work well for oil and containers where clients are either purchasing a small segment of the ship and their goods fit in 40' containers or they're buying millions of barrels of oil and need to move it halfway around the world. These ships are also port/canal limited. Most of the megaships cannot traverse the Suez or Panama canals and get forced to take the long way around, which can increase shipping time, and many of them cannot use most ports in the world. The new megacontainer ships are extremely limited because existing ports need to spend a significant chunk of capital to increase their capacity. Oil tankers, on the other hand, can lighter off the coast and either use offshore booms to transfer to shore via undersea pipelines or offload onto smaller tankers who take it into port. The biggest driver in shipping costs is fuel. Yes, shipping is efficient in a tonnes/gallon ratio sense, but it still ain't cheap to fill up the tank. As oil prices plummet, it reduces the costs of operating tankers which increases the profit margin for the operating company and allows them to reduce prices in order to gain business. The second biggest driver is business. Companies position their assets where business is and if a lot of people have put their ships near the business, the business can negotiate a lower rate which will push the BDI down in price. Source: I've built systems designed to track the maritime shipping market and the impact on commodities.