NEW YORK (CNNMoney.com) -- Suspicious trading activity surrounding the recent company acquisitions has raised questions about leaks of confidential financial information, the Wall Street Journal reported Friday.

The suspicious trade activity is not only confined to the companies' stock but includes questionable activity in obscure financial markets such as contracts tied to bonds, according to the newspaper.

The transactions range from the enormous, such as HCA (up $0.13 to $49.32, Charts)'s $21 billion buyout by private investment firms, to the miniscule, such as the $2.6 million sale of Maverick Tube Corp. to Argentina-based Tenaris SA, the Wall Street Journal reported.

As deals become more complicated and longer to complete, more banks and law firms have become involved, increasing the number of people with foreknowledge of market moves, the newspaper wrote.

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