With South African mine workers back on the job, and supplies of platinum and palladium still tight, mining companies no longer have an incentive to keep prices from rising, WallStreetJournal reports.

South Africa’s five-month long strike — its longest ever — cost mining companies about $2 billion and hurt South Africa’s economy, but it also pushed platinum prices to eight-month highs and palladium to the highest in 13-plus years.

The end of the mining strike may do more to lift the prices of platinum and palladium than the strike itself, analysts at Bank of America Merrill Lynch said, according to the WallStreetJournal.

Now that the strike is over, the metals’ prices are rallying even higher.

On Tuesday, platinum rose to $1,506.80 a troy ounce, its highest in almost 10 months. Palladium traded at $852.80 an ounce, about $8 shy of a new 13-year high. South Africa is the world’s largest second-largest palladium producer and is No. 1 for platinum, both used mainly in automobile-exhaust filters.

A large reason for the rally, analysts said, is that mining companies no longer have an incentive to keep prices down. Rising metals prices would have helped mine workers and the unions make a better case for pay raises. They could have argued that mining companies were making money on the higher-priced metals and were therefore better able to meet union demands.

Now that the strike is over, “this cap on rallies has been removed,” BofA Merrill Lynch analysts said in a note to clients, WallStreetJournal reports.

Analysts said it will be months before the production approaches levels it reached before the strike, keeping supplies tight and prices high. The losses during the strikes may also force miners to reduce their capacities.

On the demand side, analysts say auto sales are surging in China, the U.S., and the European Union. Simultaneously, authorities around the world are tightening emission standards, a move that is likely to keep prices up, according to BoFA Merrill Lynch.

Merrill Lynch’s year-end target on palladium is $790 an ounce and palladium is $1,551 an ounce. Analysts said those numbers will likely go higher.