Copper and aluminum futures closed at more-than-six-year lows in London on Monday, as a sharp decline in Chinese equities triggered a broad-based commodities rout over fears that the world’s biggest consumer of base metals is heading into a steeper-than-expected economic slowdown.

The London Metal Exchange’s three-month copper contract was down 2% at $4,953 a metric ton at the PM kerb close, having tumbled to its lowest level since 2009 earlier in trading at $4,855 a ton. It fell below the key $5,000 level for the fifth-straight session. Aluminum, meanwhile, closed down 1.7% at $1,521.50 a ton, after hitting a six-year low during trading at $1,506 a ton.

But commodities across the board were lower, with the S&P GSCI index, a broad measure of the sector, at its lowest since October 1999.

Monday’s losses came after the Shanghai Composite Index declined more than 8%, bringing its losses since a mid-June peak to about 37%. China consumes more than 40% of global base-metals supply, and as a result, metal prices tend to mirror its economic trajectory closely. When it is seen to be in trouble, market participants anticipate demand declines and price falls.

“Base metals are deeply in the red, amidst a commodity selloff as Chinese equities tumbled,” said Dee Perera, a base metals analyst at Marex Spectron.

Looking ahead, investors remain bearish on commodities, along with some other financial markets.

Analysts now debate how big an effect the Chinese slowdown will continue to have on metals prices. Few expect an immediate positive turn, but some analysts argue that in the medium-to-long term China’s appetite for metals will increase, even if not at the growth rates seen over the last decade.

“Even if [China] has been growing at 7% and it’s going to grow at 6%, that still means more metal is consumed,” said William Adams, head of research at Fastmarkets. “Let’s not forget, China is a massive economy.”

All the other base metals closed down on day. Zinc closed down 3.4% at $1,707 a ton, nickel closed down 6.7% at $9,520 a ton, lead closed down 2.5% at $1,659 a ton and tin closed down 5.7% at $14,050 a ton.