Jeffrey Gundlach tried to steal a business worth hundreds of millions of dollars after he failed to become the head of his former employer, Trust Company of the West, an attorney for TCW said in court on Thursday.

"This was an inside job," TCW attorney John Quinn told jurors.

"Even though he was so highly paid, you are going to hear he was bitter, he was unhappy, he wanted more power, he wanted more money. He wanted to be CEO," Quinn said.

The trial pits Gundlach, known as the "king of bonds," against his former employer in a proceeding that could be worth hundreds of millions for the winner.

TCW fired Gundlach, its former chief investment officer, in late 2009. In the following weeks, Gundlach set up his own asset management firm, DoubleLine Capital, and over 40 TCW employees who had worked under him migrated to the new firm.

TCW sued him shortly thereafter for theft of trade secrets and creating unfair competition in the market, among other allegations.

Gundlach counter-sued, alleging that TCW owed him wages. TCW is a unit of French bank Societe Generale (SOGN.PA).

During Quinn's opening statement on Thursday in a Los Angeles state court, Gundlach sat in the crowd a row behind TCW Chief Executive Marc Stern, calmly watching Quinn accuse him of usurping his former employer's business. At one point, Quinn told the jury precisely where Gundlach was sitting in the courtroom.

Attorneys for Gundlach are expected to deliver their opening statement later on Thursday.

Gundlach stole so many trade secrets and confidential information that, if you printed it out, it would be 2-1/2 times the height of the Empire State building, Quinn said.

"TCW owes Mr. Gundlach nothing." Quinn said. Gundlach and his co-conspirators "plotted the destruction of TCW," he said.

The case is being argued before a 12-person jury, and is expected to last five to eight weeks.

The case in Superior Court of California, County of Los Angeles is Trust Co of the West v. Jeffrey Gundlach et al, BC429385.