Software giant

Siebel Systems

(SEBL)

said Tuesday it had agreed to acquire

OpenSite

, an Internet software provider, in an all-stock deal valued at more than $440 million.

Under the terms of the deal, each outstanding share of OpenSite will be exchanged for 0.13 of one Siebel share. Siebel said it will issue roughly 3.9 million shares, with a market value of $444 million based on Monday's closing price of 112 3/4, to complete the deal.

The deal valued OpenSite's shares at about $14.66 each. The ultimate value, though, will be based upon Siebel's closing price the day the deal is completed, which is expected by the end of the second quarter.

Siebel shares were up 2 1/2, or 2.6%, to 115 5/8, in early afternoon trading Tuesday. (Siebel closed Tuesday up 14 1/8, or 13%, at 126 7/8.)

The agreement comes weeks before OpenSite, which is based in Research Triangle Park, N.C., was scheduled to go public. The proposed price for the IPO was $13 to $15 a share, according to documents filed with the

Securities and Exchange Commission

in March. The company had planned to issue 5 million shares of its common stock.

The definitive agreement, which now requires government and shareholder approval, marks the end of a tumultuous year for OpenSite. The company filed for an IPO for the first time June 1999 and planned to go public sometime last August. The offering was postponed because of market volatility last summer.

The company then reached an agreement to be acquired by

Infospace

(INSP) - Get Report

last fall, but that deal collapsed. The company refiled for its IPO in February before agreeing to be acquired by Siebel.

"We had to take a look at which option was more attractive for our shareholders," an OpenSite spokeswoman, Shawn Ramsey-Kroboth, said. The recent market volatility and the attraction of being acquired by Siebel, which is a leading provider of sales automation and customer service software, proved to be a potent combination, Ramsey-Kroboth said. The discussions with Siebel only got under way within the last month or so, she added.

OpenSite provides software that helps companies conduct business-to-business Web auctions.

As a result of OpenSite's deal with Siebel, OpenSite canceled its acquisition of Burlington, Mass.-based online auction portal,

Bidder's Edge

.

"We're disappointed with OpenSite's change in strategy, as it was an interesting opportunity to blend a leader in sell-side dynamic pricing technology with a leader in buy-side dynamic pricing aggregation," said James Carney, president and chief executive of Bidder's Edge, in a statement. "We will continue to aggressively grow our position as the leading portal in the online auction marketplace."