NEW YORK (REUTERS) - Fashion designer Michael Kors is planning to sell a big chunk of his stake in his namesake fashion house at a time when the company's shares are at an all-time high.

Mr Kors will sell 3 million of his Michael Kors Holdings shares as part of a secondary offering of 25 million shares the company announced in a regulatory filing on Tuesday. His ownership in the company will fall to about 4.8 million shares, or 2.4 per cent down from 3.9 per cent after the sale.

The filing came after Kors shares reached a new high, closing at US$64.84 on the New York Stock Exchange on Tuesday. The stock has more than tripled since Kors' IPO in December 2011.

Michael Kors last week raised its full-year sales and profit forecast after reporting large sales increases over the holiday period, including a 41 per cent rise in comparable sales in North America last quarter. The company has been taking market share away from the like of Coach.

Sportswear Holdings Limited, a global private equity firm that is Kors' largest investor, will sell nearly 19.7 million shares, or 62.9 per cent, of its holdings in the company, leaving it with an ownership of 5.8 per cent.

Investment vehicles established to benefit the children of chief executive John Idol will sell a total 2 million shares in the offering. The company itself will receive no proceeds from the offering as all shares are being sold by investors.