Kelso & Co, Global Ship Lease's (GSL) largest shareholder, plans to significantly reduce its position in the New York-listed boxship owner.

The US private equity firm expects to sell 4.5m common shares at $12.50 each through a previously announced secondary offering.

It has also given the offer's underwriters a 30-day option to buy 675,000 more shares, offering up a $64.7m holding in GSL.

Kelso currently owns 35.8% of GSL's shares but will lower its stake to 22.8% if the offering is fully sold.

GSL will not receive any proceeds from the shares being sold by Kelso through affiliates KEP VI, KEP VIII and Maas Capital Investments.

Jefferies, Deutsche Bank Securities, and Morgan Stanley are acting as joint book-running managers in the offering.

"We believe this sale is positive for trading liquidity as it partially removes a legacy holder," Jefferies analyst Randy Giveans wrote in a note.

"We view this pullback as an attractive buying opportunity."

Kelso received 13m GSL shares in January upon converting 250,000 preferred shares after GSL redeemed 9.875% secured notes maturing next year.

"We reiterate our buy rating on the name and view today's pullback as an attractive entry point," he added.

GSL's shares, which are listed on the New York Stock Exchange under the ticker symbol GSL, slipped 4.2% to $13.46 by Friday's mid-day trading on Wall Street.