The strong freight demand that has delivered bumper earnings for trucking companies during the pandemic appears to be waning, as inflation and sagging consumer sentiment slow an inventory restocking rush that has swamped distribution networks.

Rates on trucking’s spot market are sliding and analysts have started to downgrade companies in the sector as truckers prepare to report first-quarter earnings in a market that is signaling growing economic uncertainty.

The Cass Freight Index measure of domestic shipping demand edged up a bare 0.6% in March from the month before, an unseasonable slowing of growth at the end of the quarter. Freight-payment company Cass Information Systems Inc. said in an analysis of its closely watched index that the freight market is clearly in a slowdown.

At the same time, freight rates appear to be pulling back from recent historic highs.