According to a recent regulatory filing, the activist investor Carl Icahn has increased his ownership of the natural and organic products company The Hain Celestial Group. TheStreet.com reports that Icahn—who has been called “the shrewdest investor on the planet”—now owns 6.537 million shares, or nearly 15% of the Melville, New York-based company.

Icahn, who was already the largest Hain Celestial shareholder, increased his stake in the company by about 30% since September, when it was last reported that Icahn owned 5.04 million shares. In July, Hain Celestial agreed to add Icahn’s son and Icahn Capital Managing Director David S. Schechter to its board in return for Icahn supporting the company’s current directors. Under the terms of the deal, Icahn can acquire up to 20 percent of Hain Celestial’s total outstanding shares.

An opportunistic investor

In August, Nutrition Business Journal spoke to Hain Celestial President and CEO Irwin Simon about Icahn’s ownership in the company.

“Carl Icahn is a smart guy,” Simon said. “He likes what we're doing and likes our brands. I look at him as an opportunistic investor. This is one of his first forays into this category. I think he walked around Whole Foods, saw our presence there, and that's what got him excited.”

A well-known corporate raider, Icahn is currently battling to buy the film studio Lionsgate. As his shares grow in Hain Celestial, some may be wondering whether he will make a move on the natural and organic products company. The Institutional Investor’s Stephen Taub doesn’t think that will happen anytime soon, however, given the terms of the agreement inked between Icahn and the company in July.

“Hain stresses in a regulatory filing that so long as it is in compliance with its obligations under the agreement, Icahn will not participate in or actively assist a third party in a proxy fight at the 2010 meeting,” Taub wrote in September. ”Icahn also promised not to encourage anyone to oppose Hain’s slate of director nominees.”

Hain Celestial beat analyst expectations with the earnings report for the first quarter of its fiscal 2011 year. The company’s revenues were up nearly 12% to $258 million for the quarter, ended Sept. 30, 2010.

Read more of NBJ’s conversation with Hain Celestial’s Irwin Simon and Institutional Investor’s take on Icahn’s growing stake in the company.