He believes that his "termination was motivated by an agenda unrelated" to his performance, Reuters reports.
The company breached his contract by failing to pay his 2015 bonus and long-term incentive share and by not converting some of his Class D units into Energy Transfer Equity common units, the lawsuit alleges, Reuters adds.
He also was allegedly not granted the opportunity to invest in or be given an interest in Energy Transfer's Lake Charles, Louisiana liquefied natural gas project, as previously promised.
Welch was let go last month after he helped orchestrate the company's proposed acquisition of rival Williams Cos. (WMB).
Separately, TheStreet Ratings team rates the stock as a "hold" with a ratings score of C.
Energy Transfer Equity's strengths such as its impressive record of earnings per share growth and compelling growth in net income are countered by weaknesses including a generally disappointing performance in the stock itself and poor profit margins.
You can view the full analysis from the report here: ETE
TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this article's author.