(Reuters) – Palladium prices plummeted around 7 percent on Wednesday, the biggest daily percentage drop in more than two years, as investors worried that prices had risen too far too fast and breaks below technical levels triggered automatic selling.

Palladium, used to curb harmful emissions from vehicle engines, had almost doubled to a record high of $1,620.52 an ounce last week from $832 in August last year.

But it was down 6.7 percent at $1,444.51 an ounce at 2:13 pm est (1813 GMT), its second day of steep losses and the biggest plunge since January 2017.

Helping trigger the declines were comments by chief executive of miner Anglo American, who said palladium was a “bubble” and auto makers who account for some 80 percent of demand could replace the metal with cheaper platinum, said ICBC Standard analyst Marcus Garvey.

But Garvey said prices were likely to end the year around $1,500.

“It’s not the beginning of a huge re-evaluation … you still have a market that is fundamentally in industrial deficit,” he said, adding that substitution of palladium for platinum is some time away and it will be gradual if it happens.

The price fall gained momentum as palladium broke below technical levels, triggering automated selling, a trader said.

Palladium fell out of a steep upward trend channel and below its 50-day moving average for the first time since August.

Investors were also happy to sell metal for a profit after the rally, said Tai Wong, head of base and precious metals derivatives trading at BMO.

Some analysts had warned that prices could not sustain their high levels, particularly as auto sales have weakened in key markets including Europe and China, meaning car makers may need less metal.

Concerns over the health of the global economy pushed down world stock markets on Wednesday.

“It seems that global recession fears start to hurt palladium as well,” Commerzbank analyst Carsten Fritsch said.

The gloomy economic outlook offered only limited support to gold, traditionally seen as a safe investment in times of uncertainty, which dipped 0.4 percent to $1,310.56 an ounce.

A stronger dollar helped push prices lower by making bullion more expensive for non-U.S. buyers. [USD/] [US/]

Gold had on Monday risen to $1,324.32, the highest in more than three weeks.

U.S. gold futures settled down 0.3 percent at $1,310.4 per ounce.

Investors were looking ahead to the latest round of China-U.S. trade negotiations in Beijing on Thursday, as well as a fraught week for the UK as Prime Minister Theresa May attempts to push through her twice-rejected Brexit deal.

Silver was down 0.9 percent at $15.29 an ounce and platinum was 0.1 percent lower at $854 an ounce.