The Justice Department is looking into whether some of the largest hedge funds talked about trading against the euro as Greece’s crisis threatened the financial stability of the region, according to a report in The Wall Street Journal.

Major hedge fund firms such as SAC Capital Advisors, Greenlight Capital, Soros Fund Management and Paulson & Co. have been asked by Justice to hold onto correspondence and records related to their trading in euros, the report said.

As the New Year began, a Europe that had been pummeled by the recession discovered that it had a financial Achilles heel in Greece, which could default on billions in debt. That put pressure on the euro which has been declining in value against the dollar since December.

The Journal reported that managers from the big hedge fund firms gathered recently at dinner during which the euro was a topic of discussion.

However, showing that hedge fund managers discuss macro economic issues and proving that they traded in collusion with one another are two very different things, according to hedge fund attorney Ron Geffner of Sadis & Goldberg.

“There’s nothing inappropriate about people talking about their investment or pieces of their investments. The difficult part is showing that they’re acting in concert,” Geffner said.

Another question is whether a trade against the euro would have the kind of major effect that ought to trigger a serious investigation, even by a very large hedge fund.

“It would seem difficult to comprehend the amount of assets that might be required to materially influence the value of the euro,” Geffner said.

“There’s a negative bias against the fund industry that fund managers have enough assets at their disposal to corner the market to control or influence the market on underlying investments,” he said.