Reid Bigland has filed a whistleblower lawsuit against his employer for, he claims, retaliating for his cooperation with federal investigators.

According to his lawsuit, Reid Bigland, head of US sales for Fiat Chrysler (FCA) and chief of the Ram brand, says he has been cooperating with a Securities and Exchange Commission (SEC) investigation into the company's sales reporting practices, including allegations it had wrongfully inflated numbers.

The executive has testified "at length" to the SEC about the FCA's sales reporting techniques, which have reportedly been in use for at least 30 years and were well known throughout the automaker.

After refusing to admit to any personal wrongdoing, Bigland sent a letter to the SEC detailing the company's methods.

In his deposition, Reid claims FCA was displeased with the letter and his earlier sale of FCA shares, and retaliated by holding back performance incentives, effectively slashing his pay by 90% and costing the executive an estimated US$1.8 million ($2.6 million).