Scorpio Bulkers announced plans to launch a public share offering, with its private sponsor gearing up to participate with a cash injection into the New York-listed shipowner.

The Emanuele Lauro-led company said it will offer 20 million shares in the public portion of the offering, with the funds to be spent on the catchall "general corporate purposes".

Underwriters will receive options for another 3 million shares.

Scorpio Services Holding, a private company controlled by Lauro's Lolli-Ghetti family that is Scorpio Bulkers' largest shareholder, will spend $15m. The company already controls 15.8% of the Monaco and New York-headquartered bulker owner.

Scorpio Bulkers' shares plunged 8.9% to $2.94 in after-hours trading just minutes after the new offering was announced.

At that price, the offering would raise $67.6m if all options are exercised. But the share issue is yet to be priced.

The new offering will sell a large stake in the company, which has 49.7 million shares currently outstanding. The newly issued shares will represent 31.6% of the updated 72.7 million share count, if underwriters exercise all of their options.

Scorpio's last share offering in March was met with harsh criticism from former shareholder Monarch Alternative Capital, which expressed a "general lack of confidence" fuelled by the "highly dilutive offering".

Clarksons Platou Securities is the sole bookrunner and a joint lead manager on the deal, with BTIG, Pareto Securities and Stifel also serving roles as joint lead managers.