Closely watched investors George Soros and John Paulson added to their positions in the largest gold ETF in the second quarter, according to regulatory filings.

Paulson & Co. owned 21.8 million shares in SPDR Gold Shares (NYSEArca: GLD) by the end of June, up about 26% from 17.3 million shares from the end of the first quarter, Reuters reports. “The gamble resulted in a paper gain of nearly $583 million for the company as the value of its ETF holdings rose to $3.39 billion from $2.81 billion,” it said.

Paulson’s $21 billion hedge fund has more than 44% of its U.S. traded equities tied to gold, Bloomberg News reports. GLD is the firm’s largest position.

Also, Soros more than doubled his shares in the gold ETF.

GLD lost about 4% in the second quarter on weaker gold prices.

Other prominent hedge fund managers cut their stakes in the gold ETF. Eton Park Capital’s Eric Mindich had dissolved his stake by the end of the second quarter, according to the Reuters report. Eton Park owned more than $1.5 billion worth of call options and GLD common shares at the end of the first quarter.

Vinik Asset Management, the hedge fund founded by former Fidelity manager Jeffrey Vinik, also cut its entire stake in GLD, according to reports.

SPDR Gold Shares

Full disclosure: Tom Lydon’s clients own GLD.