June 18 (Bloomberg) -- WebMD Health Corp., a provider of online health information, agreed to buy parent Hlth Corp. in an all-stock deal valued at $1.29 billion. It’s the second time the interlocked companies have tried to merge in 16 months.

Holders of each Hlth share will receive 0.4444 share of WebMD. The deal values Hlth 5.7 percent higher than its $1.22 billion market capitalization at yesterday’s $11.76 a share closing price on the Nasdaq Stock Market. Hlth, of Elmwood Park, New Jersey, owns about 80 percent of New York-based WebMD, the companies said today in a statement.

WebMD’s previous attempt to acquire Hlth failed in October over trouble finding a buyer for Porex, a second unit of Hlth that makes plastics used in health and consumer products. Hlth “will be continuing its sales process for Porex with potential buyers and is aiming to conclude that process as quickly as possible,” the companies said today.

The deal will simplify the companies’ corporate structure and increase the ability of shareholders to trade WebMD, the companies said. The tax-free transaction will close in the third or fourth quarter, the companies said. WebMD will assume Hlth’s debt.

Hlth rose $1.50, or 13 percent, to $13.26 at 4 p.m. New York time in Nasdaq Stock Market composite trading, its biggest percentage gain since Feb. 21, 2008. WebMD increased $2.11, or 7.5 percent, to $30.32.

Financial advisers were Raymond James Financial Inc. for Hlth and Morgan Joseph & Co. for WebMD. Legal advisers were Shearman & Sterling LLP for Hlth and Cahill Gordon & Reindel LLP for WebMD.

To contact the reporter on this story: Catherine Larkin in Washington at clarkin4@bloomberg.net.

Last Updated: June 18, 2009 16:12 EDT