Other notable adjustments included paring stakes in Netflix , Citigroup , and Wells Fargo , but raising its shares of Pandora Media and Salesforce.com .

Soros Fund Management also dramatically boosted its shares in BlackRock — the world's largest asset management firm, overseeing $6 trillion — by nearly 60 percent to 12,983 total shares in the second quarter.

Soros Fund Management added Facebook , Apple , and Twitter , but trimmed stakes in Alphabet and Amazon.com in the quarter through June, according to a regulatory filing on Tuesday.

Soros Fund Management took share stakes in Facebook of 159,200 class A shares during the second quarter and 54,500 shares in Apple.

A number of prominent fund managers sharply cut their holdings in Apple only weeks before it became the first publicly traded U.S. company to be worth more than $1 trillion.

David Einhorn's Greenlight Capital slashed its stake by 77 percent, while Philippe Laffont's Coatue Management unloaded 95 percent. Advisory firm Diamond Hill Capital Management cut its stake by 27 percent.

Other big holders, including Sanders Capital and Adage Capital Partners, only trimmed small amounts in the second quarter.

Soros also rejigged his energy holdings, raising stakes in Devon Energy and Kinder Morgan, while dissolving his stake in the VanEck Vectors Oil Services ETF and cutting exposure to Canadian Natural Resources and Williams Companies.

Quarterly disclosures of hedge fund managers' stock holdings, in what are known as 13F filings with the U.S. Securities and Exchange Commission, are one of the few public ways of learning what the managers are selling and buying.

But relying on the filings to develop an investment strategy comes with some risk because the disclosures come 45 days after the end of each quarter and may not reflect current positions. Still, the filings offer a glimpse into what hedge fund managers saw as opportunities to make money on the long side.

The filings do not disclose short positions, or bets that a stock will fall in price. As a result, the public filings do not always present a complete picture of a management firm's equities holdings.