Glencore Plc investor Harris Associates LP, one of the biggest shareholders in the commodity trader and miner, is betting this year’s worst performer on the U.K.’s benchmark stock index will recover.

Harris increased its stake to 4.5 percent by buying shares in the past 30 days as Glencore tumbled, said David Herro, chief investment officer for international stocks. Harris is now Glencore’s fourth-largest shareholder with the stake worth about $1.6 billion based on Monday’s closing price. It owned about 1 percent of the company as of June 30, according to public filings, and hasn’t previously disclosed its increased holding.

“We like their copper position, we like their trading position,” Herro, who manages the $29-billion Oakmark International Fund, said in a phone interview. “Their other metals don’t seem to be anywhere near as impaired as iron ore. They are well-positioned.”

Glencore, which has lost 42 percent this year as commodities slumped to a 13-year low, gained for the first time in six days on Tuesday, rising as much as 2 percent to 173.5 pence in London trading.

U.K. newspaper The Telegraph over the weekend described Herro as an activist investor building a stake to pressure billionaire Chief Executive Officer Ivan Glasenberg. Herro denied this.

‘Value Shop’

“We have not invested in this as activist shareholders, we’ve made this investment as long-term value investors,” Herro said. “The business at this price is substantially undervalued. We are a long-only value shop.”

Commodity prices have retreated as China’s economy expands at the slowest pace in a quarter of a century. The Asian country is the biggest consumer of raw materials. Iron ore delivered to China has dropped 20 percent this year.

A spokesman for Baar, Switzerland-based Glencore declined to comment.

Peter Grauer, the chairman of Bloomberg LP, the parent of Bloomberg News, is a senior independent non-executive director at Glencore.

• [Editor:Juan]