Updated from 9:45 a.m. EDT

Shares of WCI Communities ( WCI) surged 15% Tuesday after activist investor Carl Icahn launched a $22-per-share buyout bid for the homebuilder.

The stock, which has sunk over the past year because of the homebuilder's exposure to a rapidly slowing Florida market, rose $2.83 to $21.80 on the day.

The bid is structured as an "any and all" tender offer by Icahn and his affiliates, High River Partnership and Icahn Management. That means the offer isn't subject to any minimum condition.

The tender offer is contingent upon WCI dropping its recently adopted poison pill, which prevents any one shareholder from accumulating too high of a stake in the company.

Icahn said he would propose his own slate of board members if WCI does not drop the poison pill and allow the tender offer. The billionaire financier has already said he plans to nominate directors to the board, a move WCI has resisted.

"We believe that the board and CEO of WCI have not enabled the Company to maximize the potential of its unique set of assets which trade at a discount to their GAAP book value," Icahn said in a statement Tuesday. "If elected, we expect our slate, in a manner consistent with their fiduciary duties, to ensure these unique assets are properly marshaled through the current residential housing industry downturn."

WCI's stock closed at $18.97 Monday, which represents a 20% discount to its book value. The Icahn offer comes in right near book value.

After Tuesday's closing bell, WCI said it will review Icahn's proposal, but it urged shareholders to make no action on the tender offer until the board issues a recommendation.

In the meantime, the company plans to continue its strategic review into alternatives, including a potential sale.

Icahn already owns 14.6% of WCI. Heavy-hitting hedge funds D.E. Shaw and Citadel each purchased stakes in the company over the past few weeks, according to Securities and Exchange Commission filings. Hedge fund giant S.A.C. Capital already owns about 7.8% of WCI.

Last month, WCI reported a fourth-quarter loss of $64.6 million, as results were dragged down by land impairment losses totaling $91.4 million. The company's housing developments and condo towers in Florida represent about 85% of its business.

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