The CFTC said the measures would affect only the 10 biggest position holders, if implemented immediately.

It said the limits, if implemented, would affect the 10 biggest position holders in all markets.

Tech now accounts for nearly a quarter of Morris-Eyton's portfolio, and SAP is his biggest position.

Loeb obviously gambled big on the shiny metal, saying it was his biggest position during the month.

Viking Global Investors nearly doubled its position to 9 million shares, listing Facebook as the fund's biggest position.

The biggest position heading into Monday was held by Discovery Capital Management, with 3.1 percent, the FCA said.

The fund manager kept his biggest position in SPDR Gold Trust, which was also unchanged at 31.5 million shares in the first quarter.

One of Belisle's biggest positions is in technology services company CGI.

Landis said one of his funds' biggest positions was Corning.

But that tells you something about who is likely to be holding the biggest positions in any one market.

Buffett has said only the changes in Berkshire's biggest positions, like adding to holdings of Wells Fargo, were made by him.

Buffett has said only the changes in Berkshire's biggest positions, like adding to holdings of Wal-Mart or Wells Fargo, were made by him.