DEERFIELD, Ill. (TheStreet) -- CF Industries (CF) - Get Report, engaged since January in a hostile bid for Terra Industries (TRA) , announced today that it bought 7% of its hoped-for prey on the open market over the last two weeks.

That amounts to nearly 7 million Terra shares, CF said in a regulatory filing and press release, at a cost of $247 million, or $35.29 a share.

Shares of Terra were trading Monday morning at $36.17, up 98 cents, or about 3%. CF Industries, meanwhile, saw its stock price inch higher by 81 cents to $85.10.

CF has used its bid for Terra partly as a way to thwart its own hostile suitor,

Agrium

(AGU)

. The three-part storyline of bids and countermoves, motivated by depressed market values amid the bear market, has enthralled the fertilizer world since the drama began early this year.

Also Monday, CF said it sent another letter to Terra describing its proposed deal, under which Terra stockholders would receive 0.465 CF shares for each Terra share. CF said it would adjust the ratio once Terra distributes its previously announced dividend of $7.50 a share.

As for CF shareholders, they would receive a portion of 5 million "contingent future shares, "which would convert based on CF's stock price trading above $125, a target increased from the previous $115 level "to reflect the overall increase in the market."

CF also said it already satisfied antitrust regulatory hurdles in both Canada and the U.S.

"Our proposal provides a very significant premium to Terra stockholders, which is above historical premiums for stock transactions," Stephen R. Wilson, CF's chief executive, said in the press release.

-- Written by Scott Eden in New York

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Scott Eden has covered business -- both large and small -- for more than a decade. Prior to joining TheStreet.com, he worked as a features reporter for Dealmaker and Trader Monthly magazines. Before that, he wrote for the Chicago Reader, that city's weekly paper. Early in his career, he was a staff reporter at the Dow Jones News Service. His reporting has appeared in The Wall Street Journal, Men's Journal, the St. Petersburg (Fla.) Times, and the Believer magazine, among other publications. He's also the author of Touchdown Jesus (Simon & Schuster, 2005), a nonfiction book about Notre Dame football fans and the business and politics of big-time college sports. He has degrees from Notre Dame and Washington University in St. Louis.