NEW YORK (Reuters) - Southwest Airlines Director Rakesh Gangwal, who was picked by the company to join its board amid growing pressure from an activist investor, bought more than $100 million in stock and said on Wednesday more top level leadership changes would be "counterproductive."

Gangwal, who co-founded low-cost Indian carrier InterGlobe Aviation, or IndiGo, purchased 3.6 million Southwest ( LUV ) shares on September 30 and October 1 according to Securities and Exchange Commission filings. He paid between $29 and $30 a share.

He said he made the purchases as soon as the so-called trading window when directors and other insiders are permitted to buy and sell the stock opened.

Southwest ( LUV ) put Gangwal on the board in July as activist investor Elliott Investment Management increased pressure on the carrier, demanding leadership and strategy changes to improve financial performance. The company last month announced a board overhaul and other changes.

Last month Southwest ( LUV ) said executive chairman Gary Kelly will step down and six other directors will retire from its 15-member board.

Elliott has held firm to demands for more changes in the top ranks, including the ouster of CEO Bob Jordan. Last week it said it plans to request a special shareholder meeting to press for those changes.

Gangwal told Reuters on Wednesday that more upheaval in the executive suite and boardroom would hurt shareholders. "I believe changing the board structure and top leadership beyond what has been already announced, would be counterproductive and not in the best interest of shareholders."