In a December interview with TheStreet. com Cramer, a popular Wall Street commentator and hedge fund manager, advocated a litany of questionable market practices designed to manipulate stock prices and prompt competing traders to buy or sell at a disadvantage.

Describing some of the tactics as "blatantly illegal", Cramer said hedge fund managers should plant misinformation, feed "bozo" reporters lies and take tactical positions in stocks to convince "moron" traders to follow suit.

He insisted that the mechanics of trading were "much more important than fundamentals".

The interview only became widely known last week when it was posted on YouTube, but the comments stirred speculation that Cramer's past trades will be investigated.