Palladium is one of the many metals used in catalytic converters to quell and contain internal combustion engine emissions, and now it’s getting hellaciously expensive. The price of palladium has been increasing drastically over the last four years, but has ballooned 25% in the last two weeks, .

In January of 2016 a Troy ounce of palladium would cost manufacturers about $500. Today that same ounce is over $2500.

A catalytic converter is one of those car parts that you know how it works in theory, but you’re…

“There’s no metal,” a trader in London told Reuters. “Consumers are stockpiling. It’s all been shipped to China.”

Apparently the demand for palladium is expected to be about 10 million ounces in 2020 and 2021, while mining supply can just barely fulfill 9 million of those ounces. South Africa, where about 40 percent of platinum group metals—including palladium—are mined, recently reported a reduction in output of 13.5 percent.

New Chinese regulations require at least 30% more palladium per vehicle, which is causing a huge crunch in the already limited supply of the metal. The average passenger car requires just a few grams of platinum group metals per catalytic converter, but trucks and SUVs with large engines can require up to a full ounce (about 31 grams) of the stuff to meet emissions standards.

So there’s a decline in supply while demand continues to rise? I’m not good at economics, can someone explain what happens when demand exceeds supply?

In addition to palladium, catalysts also make use of a blend of platinum, cerium, copper, iron, manganese, nickel, , and rhodium. Some of these are also quite expensive, like rhodium which runs around $2750 per ounce. If you’ve ever wondered why replacing a catalytic converter is so expensive, or why thieves like to cut them out of trucks, this might help explain it.