Earlier this week, I asked the question whether insider trading was back. That was after a Credit Suisse investment banker was arrested for dirty deals involving the $45 billion TXU buyout.

Now it continues with reports of the Securities and Exchange Commission filing a lawsuit against a Hong Kong couple for insider trading around the News Corp. bid for Dow Jones.

According to the report, Hong Kong businessman Michael Leung had close links with David Li, a Dow Jones director. Both men are high ranking insiders at the Bank of East Asia Ltd., the biggest locally owned banking group in Hong Kong. Li has not been accused of any wrongdoing and has denied disclosing any information.

So what's going on? Is this a trend? Earlier this week, I asked whether new communications technologies and global markets were making it easier.

But there are other reasons. Like for example the private equity boom.

Private equity can create fertile territory for this sort of activity, reports Bloomberg's David Scheer .

The worrying part about so many private equity deals is that they create the potential for insider trading by roping in senior management and directors to participate in the transaction. That increases the chances of insider trading if employees or partners in the private equity firm decide to buy or sell securities using material non-public information learned from directors of the target companies.