The reason for capesize bulker spot rates' downward trend can be summed up in one word, according to brokers and analysts: volatility.

The capesize 5TC, a weighted average of spot rates across five routes, has dropped 26% since 10 May to $31,429 per day on Tuesday, the lowest level in a month.

"My take on it is that the larger vessels carry a smaller range of cargoes and therefore are more prone to volatility and sentiment related to those cargoes or external factors such as geopolitical events," said Rebecca Galanopoulos Jones, research analyst for London broking house Alibra Shipping.