Activist shareholder and investor and Wall Street's richest trader Carl Icahn spoke about being investigated on insider trading with Phil Mickelson and William Walters.

"We do not know of any investigation. Further, we are always very careful to observe all legal requirements in all of our activities. We believe that making inflammatory and speculative statements, especially when we've had an unblemished record for 50 years, is completely irresponsible on the part of the Wall Street Journal," Icahn told Bloomberg Television's Trish Regan.

"I am very proud of my 50-year unblemished record and have never given out insider information," Icahn told Reuters. He added that he was unaware of any FBI and SEC investigation. He upheld that his firm had always been legal. He admitted having business with Walters but denied knowing Mickelson on a personal level.

The FBI and Securities and Exchange Commission (SEC) are leading the investigation together with federal prosecutors in Manhattan. As alleged, Icahn revealed information about his bet on Clorox to Walters and the latter passed the information to Mickelson, The Wall Street Journal reported on May 30.

Icahn was reportedly placing a takeover bid for Clorox when Mickelson and Walters made their trades. During the time of the trading, SEC asked for Icahn to submit himself to a routine information request on his dealings with Clorox, The New York Times reports.

The investigation had been ongoing for two years but no probable evidence of the alleged insider trading was established. The feds went as far as examining call logs from Icahn's phone in order to check if the three big time investors were contacting each other after the questionable trading.

Icahn's bid in question failed and there was an indication that if he did reveal information about his firm's bid on Clorox, the revelation was done in good faith. His act would only be illegal if he breached a duty of confidentiality against his investors - an angle that still needs in depth investigation.

Icahn announced his plan of a bid to takeover Clorox back in 2011, The New York Times noted. Through a regulatory filing, it was revealed that his firm was already able to acquire significant Clorox shares under the impression that the stock was undervalued. Around this time, shares of Clorox jumped at about 6 per cent after Icahn's announcement and disclosed of his stake.

Months following his first announcement, Icahn announced another unsolicited takeover bid and penned a letter to Clorox proposing to purchase the company for $76.50 per share. He emphasised that his firm was the stock's largest investor.

According to financial reports circulating around that time, unusual trading activities in shares of Clorox and options to buy the stock occurred following Icahn's series of announcement. For this reason, Financial Industry Regulatory Authority (Finra) started investigating the Clorox trading. The agency saw well-timed trading from Walters and Mickelson coinciding with Icahn's takeover bid.

Conversely, Clorox rejected Icahn's takeover bid and by September 2011, Icahn pulled the bid out.

The profundity of the relationship among the three men in question cannot be clearly established but The New York Times noted that Icahn and Walters were both investors in Las Vegas real estate. Icahn is chairman of the casino company Tropicana Entertainment. Walters on the other hand controlled a Nevada company with business partners being investors in Voltari that Icahn is one of the largest shareholders.

Curiously, during a 2011 interview with 60 minutes, Walters said that he failed in stocks as compared to his success in sports. He mentioned that he met the worst investment crooks on Wall Street.